From ce549a858346121c352461fac26253292679effb Mon Sep 17 00:00:00 2001
From: Dylan Falconer <me@falconerd.com>
Date: Tue, 6 Sep 2022 14:29:12 +1000
Subject: [PATCH 1/7] Simple makefile for linux

---
 Makefile | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
 create mode 100644 Makefile

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..6589d56
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,16 @@
+render=src/engine/render/render.c src/engine/render/render_init.c src/engine/render/render_util.c
+io=src/engine/io/io.c
+config=src/engine/config/config.c
+input=src/engine/input/input.c
+time=src/engine/time/time.c
+physics=src/engine/physics/physics.c
+array_list=src/engine/array_list/array_list.c
+entity=src/engine/entity/entity.c
+files=src/glad.c src/main.c src/engine/global.c $(render) $(io) $(config) $(input) $(time) $(physics) $(array_list) $(entity)
+
+libs=-lm `sdl2-config --cflags --libs`
+
+#CL /Zi /I W:/include $(files) /link $(libs) /OUT:mygame.exe
+
+build:
+	gcc -g3 $(files) $(libs) -o mygame.out

From 8be621c150cb984adeda075cf4bb0ec9f80c4eae Mon Sep 17 00:00:00 2001
From: Dylan Falconer <me@falconerd.com>
Date: Tue, 6 Sep 2022 14:29:53 +1000
Subject: [PATCH 2/7] Remove global render state

---
 src/engine/global.h                 |  1 -
 src/engine/render.h                 |  4 +-
 src/engine/render/render.c          | 60 +++++++++++++++++------------
 src/engine/render/render_init.c     | 18 +++++----
 src/engine/render/render_internal.h | 13 +------
 src/engine/types.h                  |  1 +
 src/main.c                          |  8 ++--
 7 files changed, 54 insertions(+), 51 deletions(-)

diff --git a/src/engine/global.h b/src/engine/global.h
index 6606f45..33dffce 100644
--- a/src/engine/global.h
+++ b/src/engine/global.h
@@ -6,7 +6,6 @@
 #include "time.h"
 
 typedef struct global {
-	Render_State render;
 	Config_State config;
 	Input_State input;
 	Time_State time;
diff --git a/src/engine/render.h b/src/engine/render.h
index 50fecf7..e6c054d 100644
--- a/src/engine/render.h
+++ b/src/engine/render.h
@@ -11,9 +11,9 @@ typedef struct render_state {
 	f32 height;
 } Render_State;
 
-void render_init(void);
+SDL_Window *render_init(void);
 void render_begin(void);
-void render_end(void);
+void render_end(SDL_Window *window);
 void render_quad(vec2 pos, vec2 size, vec4 color);
 void render_quad_line(vec2 pos, vec2 size, vec4 color);
 void render_line_segment(vec2 start, vec2 end, vec4 color);
diff --git a/src/engine/render/render.c b/src/engine/render/render.c
index bedfa34..9b3afe3 100644
--- a/src/engine/render/render.c
+++ b/src/engine/render/render.c
@@ -4,20 +4,32 @@
 #include "../render.h"
 #include "render_internal.h"
 
-static Render_State_Internal state = {0};
-
-void render_init(void) {
-	global.render.width = 1920;
-	global.render.height = 1080;
-	global.render.window = render_init_window(global.render.width, global.render.height);
-
-	render_init_quad(&state.vao_quad, &state.vbo_quad, &state.ebo_quad);
-	render_init_line(&state.vao_line, &state.vbo_line);
-	render_init_shaders(&state);
-	render_init_color_texture(&state.texture_color);
+static f32 window_width = 1920;
+static f32 window_height = 1080;
+static f32 render_width = 640;
+static f32 render_height = 360;
+static f32 scale = 3;
+
+static u32 vao_quad;
+static u32 vbo_quad;
+static u32 ebo_quad;
+static u32 vao_line;
+static u32 vbo_line;
+static u32 shader_default;
+static u32 texture_color;
+
+SDL_Window *render_init(void) {
+	SDL_Window *window = render_init_window(window_width, window_height);
+
+	render_init_quad(&vao_quad, &vbo_quad, &ebo_quad);
+	render_init_line(&vao_line, &vbo_line);
+	render_init_shaders(&shader_default, render_width, render_height);
+	render_init_color_texture(&texture_color);
 
 	glEnable(GL_BLEND);
 	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+
+	return window;
 }
 
 void render_begin(void) {
@@ -25,12 +37,12 @@ void render_begin(void) {
 	glClear(GL_COLOR_BUFFER_BIT);
 }
 
-void render_end(void) {
-	SDL_GL_SwapWindow(global.render.window);
+void render_end(SDL_Window *window) {
+	SDL_GL_SwapWindow(window);
 }
 
 void render_quad(vec2 pos, vec2 size, vec4 color) {
-	glUseProgram(state.shader_default);
+	glUseProgram(shader_default);
 
 	mat4x4 model;
 	mat4x4_identity(model);
@@ -38,19 +50,19 @@ void render_quad(vec2 pos, vec2 size, vec4 color) {
 	mat4x4_translate(model, pos[0], pos[1], 0);
 	mat4x4_scale_aniso(model, model, size[0], size[1], 1);
 
-	glUniformMatrix4fv(glGetUniformLocation(state.shader_default, "model"), 1, GL_FALSE, &model[0][0]);
-	glUniform4fv(glad_glGetUniformLocation(state.shader_default, "color"), 1, color);
+	glUniformMatrix4fv(glGetUniformLocation(shader_default, "model"), 1, GL_FALSE, &model[0][0]);
+	glUniform4fv(glad_glGetUniformLocation(shader_default, "color"), 1, color);
 
-	glBindVertexArray(state.vao_quad);
+	glBindVertexArray(vao_quad);
 
-	glBindTexture(GL_TEXTURE_2D, state.texture_color);
+	glBindTexture(GL_TEXTURE_2D, texture_color);
 	glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, NULL);
 
 	glBindVertexArray(0);
 }
 
 void render_line_segment(vec2 start, vec2 end, vec4 color) {
-	glUseProgram(state.shader_default);
+	glUseProgram(shader_default);
 	glLineWidth(3);
 
 	f32 x = end[0] - start[0];
@@ -60,13 +72,13 @@ void render_line_segment(vec2 start, vec2 end, vec4 color) {
 	mat4x4 model;
 	mat4x4_translate(model, start[0], start[1], 0);
 
-	glUniformMatrix4fv(glGetUniformLocation(state.shader_default, "model"), 1, GL_FALSE, &model[0][0]);
-	glUniform4fv(glGetUniformLocation(state.shader_default, "color"), 1, color);
+	glUniformMatrix4fv(glGetUniformLocation(shader_default, "model"), 1, GL_FALSE, &model[0][0]);
+	glUniform4fv(glGetUniformLocation(shader_default, "color"), 1, color);
 
-	glBindTexture(GL_TEXTURE_2D, state.texture_color);
-	glBindVertexArray(state.vao_line);
+	glBindTexture(GL_TEXTURE_2D, texture_color);
+	glBindVertexArray(vao_line);
 
-	glBindBuffer(GL_ARRAY_BUFFER, state.vbo_line);
+	glBindBuffer(GL_ARRAY_BUFFER, vbo_line);
 	glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(line), line);
 	glDrawArrays(GL_LINES, 0, 2);
 
diff --git a/src/engine/render/render_init.c b/src/engine/render/render_init.c
index 22b3621..a1c6857 100644
--- a/src/engine/render/render_init.c
+++ b/src/engine/render/render_init.c
@@ -20,8 +20,8 @@ SDL_Window *render_init_window(u32 width, u32 height) {
 		"MyGame",
 		SDL_WINDOWPOS_CENTERED,
 		SDL_WINDOWPOS_CENTERED,
-		global.render.width,
-		global.render.height,
+		width,
+		height,
 		SDL_WINDOW_OPENGL
 	);
 
@@ -42,17 +42,19 @@ SDL_Window *render_init_window(u32 width, u32 height) {
 	return window;
 }
 
-void render_init_shaders(Render_State_Internal *state) {
-	state->shader_default = render_shader_create("./shaders/default.vert", "./shaders/default.frag");
+void render_init_shaders(u32 *shader_default, f32 render_width, f32 render_height) {
+	mat4x4 projection;
 
-	mat4x4_ortho(state->projection, 0, global.render.width, 0, global.render.height, -2, 2);
+	*shader_default = render_shader_create("./shaders/default.vert", "./shaders/default.frag");
 
-	glUseProgram(state->shader_default);
+	mat4x4_ortho(projection, 0, render_width, 0, render_height, -2, 2);
+
+	glUseProgram(*shader_default);
 	glUniformMatrix4fv(
-		glGetUniformLocation(state->shader_default, "projection"),
+		glGetUniformLocation(*shader_default, "projection"),
 		1,
 		GL_FALSE,
-		&state->projection[0][0]
+		&projection[0][0]
 	);
 }
 
diff --git a/src/engine/render/render_internal.h b/src/engine/render/render_internal.h
index dca89b2..ea15ab1 100644
--- a/src/engine/render/render_internal.h
+++ b/src/engine/render/render_internal.h
@@ -5,21 +5,10 @@
 #include "../types.h"
 #include "../render.h"
 
-typedef struct render_state_internal {
-	u32 vao_quad;
-	u32 vbo_quad;
-	u32 ebo_quad;
-	u32 vao_line;
-	u32 vbo_line;
-	u32 shader_default;
-	u32 texture_color;
-	mat4x4 projection;
-} Render_State_Internal;
-
 SDL_Window *render_init_window(u32 width, u32 height);
 void render_init_quad(u32 *vao, u32 *vbo, u32 *ebo);
 void render_init_color_texture(u32 *texture);
-void render_init_shaders(Render_State_Internal *state);
+void render_init_shaders(u32 *shader_default, f32 render_width, f32 render_height);
 void render_init_line(u32 *vao, u32 *vbo);
 u32 render_shader_create(const char *path_vert, const char *path_frag);
 
diff --git a/src/engine/types.h b/src/engine/types.h
index a1de90a..7711a77 100644
--- a/src/engine/types.h
+++ b/src/engine/types.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <inttypes.h>
+#include <stdlib.h>
 
 typedef uint8_t  u8;
 typedef uint16_t u16;
diff --git a/src/main.c b/src/main.c
index d20ecac..1a782e4 100644
--- a/src/main.c
+++ b/src/main.c
@@ -78,7 +78,7 @@ void enemy_on_hit_static(Body *self, Static_Body *other, Hit hit) {
 int main(int argc, char *argv[]) {
 	time_init(60);
 	config_init();
-	render_init();
+	SDL_Window *window = render_init();
 	physics_init();
 	entity_init();
 
@@ -89,8 +89,8 @@ int main(int argc, char *argv[]) {
 
 	usize player_id = entity_create((vec2){100, 800}, (vec2){100, 100}, (vec2){0, 0}, COLLISION_LAYER_PLAYER, player_mask, player_on_hit, player_on_hit_static);
 
-	f32 width = global.render.width;
-	f32 height = global.render.height;
+	i32 width, height;
+	SDL_GetWindowSize(window, &width, &height);
 
 	u32 static_body_a_id = physics_static_body_create((vec2){width * 0.5 - 25, height - 25}, (vec2){width - 50, 50}, COLLISION_LAYER_TERRAIN);
 	u32 static_body_b_id = physics_static_body_create((vec2){width - 25, height * 0.5 + 25}, (vec2){50, height - 50}, COLLISION_LAYER_TERRAIN);
@@ -140,7 +140,7 @@ int main(int argc, char *argv[]) {
 		render_aabb((f32*)physics_body_get(entity_get(entity_a_id)->body_id), WHITE);
 		render_aabb((f32*)physics_body_get(entity_get(entity_b_id)->body_id), WHITE);
 
-		render_end();
+		render_end(window);
 
 		player_color[0] = 0;
 		player_color[2] = 1;

From 28f779a6450d839dcb4e04720795a31445671330 Mon Sep 17 00:00:00 2001
From: Dylan Falconer <me@falconerd.com>
Date: Tue, 6 Sep 2022 14:48:02 +1000
Subject: [PATCH 3/7] Resize bodies, change gravity, add scale getter

---
 src/engine/physics/physics.c |  4 ++--
 src/engine/render.h          |  1 +
 src/engine/render/render.c   |  3 +++
 src/main.c                   | 36 +++++++++++++++++-------------------
 4 files changed, 23 insertions(+), 21 deletions(-)

diff --git a/src/engine/physics/physics.c b/src/engine/physics/physics.c
index e99cb16..6a45bc8 100644
--- a/src/engine/physics/physics.c
+++ b/src/engine/physics/physics.c
@@ -110,8 +110,8 @@ void physics_init(void) {
 	state.body_list = array_list_create(sizeof(Body), 0);
 	state.static_body_list = array_list_create(sizeof(Static_Body), 0);
 
-	state.gravity = -200;
-	state.terminal_velocity = -10000;
+	state.gravity = -100;
+	state.terminal_velocity = -7000;
 
 	tick_rate = 1.f / iterations;
 }
diff --git a/src/engine/render.h b/src/engine/render.h
index e6c054d..e454493 100644
--- a/src/engine/render.h
+++ b/src/engine/render.h
@@ -19,3 +19,4 @@ void render_quad_line(vec2 pos, vec2 size, vec4 color);
 void render_line_segment(vec2 start, vec2 end, vec4 color);
 void render_aabb(f32 *aabb, vec4 color);
 
+f32 render_get_scale();
diff --git a/src/engine/render/render.c b/src/engine/render/render.c
index 9b3afe3..1c8cc70 100644
--- a/src/engine/render/render.c
+++ b/src/engine/render/render.c
@@ -105,3 +105,6 @@ void render_aabb(f32 *aabb, vec4 color) {
 	render_quad_line(&aabb[0], size, color);
 }
 
+f32 render_get_scale() {
+	return scale;
+}
diff --git a/src/main.c b/src/main.c
index 1a782e4..f341b32 100644
--- a/src/main.c
+++ b/src/main.c
@@ -32,20 +32,16 @@ static void input_handle(Body *body_player) {
 	f32 vely = body_player->velocity[1];
 
 	if (global.input.right) {
-		velx += 1000;
+		velx += 600;
 	}
 
 	if (global.input.left) {
-		velx -= 1000;
+		velx -= 600;
 	}
 
 	if (global.input.up && player_is_grounded) {
 		player_is_grounded = false;
-		vely = 4000;
-	}
-
-	if (global.input.down) {
-		vely -= 800;
+		vely = 2000;
 	}
 
 	body_player->velocity[0] = velx;
@@ -67,11 +63,11 @@ void player_on_hit_static(Body *self, Static_Body *other, Hit hit) {
 
 void enemy_on_hit_static(Body *self, Static_Body *other, Hit hit) {
 	if (hit.normal[0] > 0) {
-		self->velocity[0] = 700;
+		self->velocity[0] = 400;
 	}
 
 	if (hit.normal[0] < 0) {
-		self->velocity[0] = -700;
+		self->velocity[0] = -400;
 	}
 }
 
@@ -87,19 +83,21 @@ int main(int argc, char *argv[]) {
 	u8 enemy_mask = COLLISION_LAYER_PLAYER | COLLISION_LAYER_TERRAIN;
 	u8 player_mask = COLLISION_LAYER_ENEMY | COLLISION_LAYER_TERRAIN;
 
-	usize player_id = entity_create((vec2){100, 800}, (vec2){100, 100}, (vec2){0, 0}, COLLISION_LAYER_PLAYER, player_mask, player_on_hit, player_on_hit_static);
+	usize player_id = entity_create((vec2){100, 200}, (vec2){24, 24}, (vec2){0, 0}, COLLISION_LAYER_PLAYER, player_mask, player_on_hit, player_on_hit_static);
 
-	i32 width, height;
-	SDL_GetWindowSize(window, &width, &height);
+	i32 window_width, window_height;
+	SDL_GetWindowSize(window, &window_width, &window_height);
+	f32 width = window_width / render_get_scale();
+	f32 height = window_height / render_get_scale();
 
-	u32 static_body_a_id = physics_static_body_create((vec2){width * 0.5 - 25, height - 25}, (vec2){width - 50, 50}, COLLISION_LAYER_TERRAIN);
-	u32 static_body_b_id = physics_static_body_create((vec2){width - 25, height * 0.5 + 25}, (vec2){50, height - 50}, COLLISION_LAYER_TERRAIN);
-	u32 static_body_c_id = physics_static_body_create((vec2){width * 0.5 + 25, 25}, (vec2){width - 50, 50}, COLLISION_LAYER_TERRAIN);
-	u32 static_body_d_id = physics_static_body_create((vec2){25, height * 0.5 - 25}, (vec2){50, height - 50}, COLLISION_LAYER_TERRAIN);
-	u32 static_body_e_id = physics_static_body_create((vec2){width * 0.5, height * 0.5}, (vec2){150, 150}, COLLISION_LAYER_TERRAIN);
+	u32 static_body_a_id = physics_static_body_create((vec2){width * 0.5 - 12.5, height - 12.5}, (vec2){width - 25, 25}, COLLISION_LAYER_TERRAIN);
+	u32 static_body_b_id = physics_static_body_create((vec2){width - 12.5, height * 0.5 + 12.5}, (vec2){25, height - 25}, COLLISION_LAYER_TERRAIN);
+	u32 static_body_c_id = physics_static_body_create((vec2){width * 0.5 + 12.5, 12.5}, (vec2){width - 25, 25}, COLLISION_LAYER_TERRAIN);
+	u32 static_body_d_id = physics_static_body_create((vec2){12.5, height * 0.5 - 12.5}, (vec2){25, height - 25}, COLLISION_LAYER_TERRAIN);
+	u32 static_body_e_id = physics_static_body_create((vec2){width * 0.5, height * 0.5}, (vec2){62.5, 62.5}, COLLISION_LAYER_TERRAIN);
 
-	usize entity_a_id = entity_create((vec2){600, 600}, (vec2){50, 50}, (vec2){900, 0}, COLLISION_LAYER_ENEMY, enemy_mask, NULL, enemy_on_hit_static);
-	usize entity_b_id = entity_create((vec2){800, 800}, (vec2){50, 50}, (vec2){900, 0}, 0, enemy_mask, NULL, enemy_on_hit_static);
+	usize entity_a_id = entity_create((vec2){200, 200}, (vec2){25, 25}, (vec2){400, 0}, COLLISION_LAYER_ENEMY, enemy_mask, NULL, enemy_on_hit_static);
+	usize entity_b_id = entity_create((vec2){300, 300}, (vec2){25, 25}, (vec2){400, 0}, 0, enemy_mask, NULL, enemy_on_hit_static);
 
 	while (!should_quit) {
 		time_update();

From fb8646c91dcf544749744db704927c681ffa856d Mon Sep 17 00:00:00 2001
From: Dylan Falconer <me@falconerd.com>
Date: Tue, 6 Sep 2022 14:50:36 +1000
Subject: [PATCH 4/7] Fix bodies being scaled down twice

---
 src/engine/entity/entity.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/src/engine/entity/entity.c b/src/engine/entity/entity.c
index 10aa21b..98d2930 100644
--- a/src/engine/entity/entity.c
+++ b/src/engine/entity/entity.c
@@ -8,8 +8,6 @@ void entity_init(void) {
 }
 
 usize entity_create(vec2 position, vec2 size, vec2 velocity, u8 collision_layer, u8 collision_mask, On_Hit on_hit, On_Hit_Static on_hit_static) {
-	vec2_scale(size, size, 0.5);
-
 	Entity entity = {
 		.body_id = physics_body_create(position, size, velocity, collision_layer, collision_mask, on_hit, on_hit_static),
 		.is_active = true,

From 410a31e881c70c3fc434bda776cf05234455fb9a Mon Sep 17 00:00:00 2001
From: Dylan Falconer <me@falconerd.com>
Date: Tue, 6 Sep 2022 14:55:48 +1000
Subject: [PATCH 5/7] Remove render state struct type

---
 src/engine/render.h | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/src/engine/render.h b/src/engine/render.h
index e454493..e5783a5 100644
--- a/src/engine/render.h
+++ b/src/engine/render.h
@@ -5,12 +5,6 @@
 
 #include "types.h"
 
-typedef struct render_state {
-	SDL_Window *window;
-	f32 width;
-	f32 height;
-} Render_State;
-
 SDL_Window *render_init(void);
 void render_begin(void);
 void render_end(SDL_Window *window);

From 425071049449568a2d7bc5b70d5415363b8db6f1 Mon Sep 17 00:00:00 2001
From: Dylan Falconer <me@falconerd.com>
Date: Tue, 6 Sep 2022 17:16:01 +1000
Subject: [PATCH 6/7] batch quad renderer

---
 shaders/batch_quad.frag             | 11 +++++
 shaders/batch_quad.vert             | 15 +++++++
 src/engine/render.h                 | 14 +++++-
 src/engine/render/render.c          | 68 ++++++++++++++++++++++++++++-
 src/engine/render/render_init.c     | 46 ++++++++++++++++++-
 src/engine/render/render_internal.h |  3 +-
 src/main.c                          | 13 ++++++
 7 files changed, 166 insertions(+), 4 deletions(-)
 create mode 100644 shaders/batch_quad.frag
 create mode 100644 shaders/batch_quad.vert

diff --git a/shaders/batch_quad.frag b/shaders/batch_quad.frag
new file mode 100644
index 0000000..8b4d4f1
--- /dev/null
+++ b/shaders/batch_quad.frag
@@ -0,0 +1,11 @@
+#version 330 core
+out vec4 o_color;
+
+in vec4 v_color;
+in vec2 v_uvs;
+
+uniform sampler2D texture_slot;
+
+void main() {
+	o_color = texture(texture_slot, v_uvs) * v_color;
+}
diff --git a/shaders/batch_quad.vert b/shaders/batch_quad.vert
new file mode 100644
index 0000000..9a01ae0
--- /dev/null
+++ b/shaders/batch_quad.vert
@@ -0,0 +1,15 @@
+#version 330 core
+layout (location = 0) in vec2 a_pos;
+layout (location = 1) in vec2 a_uvs;
+layout (location = 2) in vec4 a_color;
+
+out vec4 v_color;
+out vec2 v_uvs;
+
+uniform mat4 projection;
+
+void main() {
+	v_color = a_color;
+	v_uvs = a_uvs;
+	gl_Position = projection * vec4(a_pos, 0.0, 1.0);
+}
diff --git a/src/engine/render.h b/src/engine/render.h
index e5783a5..cb149cb 100644
--- a/src/engine/render.h
+++ b/src/engine/render.h
@@ -5,6 +5,16 @@
 
 #include "types.h"
 
+typedef struct batch_vertex {
+	vec2 position;
+	vec2 uvs;
+	vec4 color;
+} Batch_Vertex;
+
+#define MAX_BATCH_QUADS 10000
+#define MAX_BATCH_VERTICES 40000
+#define MAX_BATCH_ELEMENTS 60000
+
 SDL_Window *render_init(void);
 void render_begin(void);
 void render_end(SDL_Window *window);
@@ -12,5 +22,7 @@ void render_quad(vec2 pos, vec2 size, vec4 color);
 void render_quad_line(vec2 pos, vec2 size, vec4 color);
 void render_line_segment(vec2 start, vec2 end, vec4 color);
 void render_aabb(f32 *aabb, vec4 color);
-
 f32 render_get_scale();
+
+// Temporary!
+void append_quad(vec2 position, vec2 size, vec4 texture_coordinates, vec4 color);
diff --git a/src/engine/render/render.c b/src/engine/render/render.c
index 1c8cc70..97b4568 100644
--- a/src/engine/render/render.c
+++ b/src/engine/render/render.c
@@ -1,7 +1,11 @@
 #include <glad/glad.h>
 
+#define STB_IMAGE_IMPLEMENTATION
+#include <stb_image.h>
+
 #include "../global.h"
 #include "../render.h"
+#include "../array_list.h"
 #include "render_internal.h"
 
 static f32 window_width = 1920;
@@ -17,27 +21,89 @@ static u32 vao_line;
 static u32 vbo_line;
 static u32 shader_default;
 static u32 texture_color;
+static u32 vao_batch;
+static u32 vbo_batch;
+static u32 ebo_batch;
+static u32 shader_batch;
+static Array_List *list_batch;
 
 SDL_Window *render_init(void) {
 	SDL_Window *window = render_init_window(window_width, window_height);
 
 	render_init_quad(&vao_quad, &vbo_quad, &ebo_quad);
+	render_init_batch_quads(&vao_batch, &vbo_batch, &ebo_batch);
 	render_init_line(&vao_line, &vbo_line);
-	render_init_shaders(&shader_default, render_width, render_height);
+	render_init_shaders(&shader_default, &shader_batch, render_width, render_height);
 	render_init_color_texture(&texture_color);
 
 	glEnable(GL_BLEND);
 	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 
+	list_batch = array_list_create(sizeof(Batch_Vertex), 8);
+
+	stbi_set_flip_vertically_on_load(1);
+
 	return window;
 }
 
 void render_begin(void) {
 	glClearColor(0.08, 0.1, 0.1, 1);
 	glClear(GL_COLOR_BUFFER_BIT);
+
+	list_batch->len = 0;
+}
+
+static void render_batch(Batch_Vertex *vertices, usize count, u32 texture_id) {
+	glBindBuffer(GL_ARRAY_BUFFER, vbo_batch);
+	glBufferSubData(GL_ARRAY_BUFFER, 0, count * sizeof(Batch_Vertex), vertices);
+
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D, texture_id);
+
+	glUseProgram(shader_batch);
+	glBindVertexArray(vao_batch);
+
+	// count >> 2 is the same as count / 4.
+	// 4 vertices per quad.
+	// 6 indices per quad (two tris).
+	glDrawElements(GL_TRIANGLES, (count >> 2) * 6, GL_UNSIGNED_INT, NULL);
+}
+
+void append_quad(vec2 position, vec2 size, vec4 texture_coordinates, vec4 color) {
+	vec4 uvs = {0, 0, 1, 1};
+
+	if (texture_coordinates != NULL) {
+		memcpy(uvs, texture_coordinates, sizeof(vec4));
+	}
+
+	array_list_append(list_batch, &(Batch_Vertex){
+		.position = { position[0], position[1] },
+		.uvs = { uvs[0], uvs[1] },
+		.color = { color[0], color[1], color[2], color[3] },
+	});
+
+	array_list_append(list_batch, &(Batch_Vertex){
+		.position = { position[0] + size[0], position[1] },
+		.uvs = { uvs[2], uvs[1] },
+		.color = { color[0], color[1], color[2], color[3] },
+	});
+
+	array_list_append(list_batch, &(Batch_Vertex){
+		.position = { position[0] + size[0], position[1] + size[1] },
+		.uvs = { uvs[2], uvs[3] },
+		.color = { color[0], color[1], color[2], color[3] },
+	});
+
+	array_list_append(list_batch, &(Batch_Vertex){
+		.position = { position[0], position[1] + size[1] },
+		.uvs = { uvs[0], uvs[3] },
+		.color = { color[0], color[1], color[2], color[3] },
+	});
 }
 
 void render_end(SDL_Window *window) {
+	render_batch(list_batch->items, list_batch->len, texture_color);
+
 	SDL_GL_SwapWindow(window);
 }
 
diff --git a/src/engine/render/render_init.c b/src/engine/render/render_init.c
index a1c6857..3311f7d 100644
--- a/src/engine/render/render_init.c
+++ b/src/engine/render/render_init.c
@@ -42,10 +42,11 @@ SDL_Window *render_init_window(u32 width, u32 height) {
 	return window;
 }
 
-void render_init_shaders(u32 *shader_default, f32 render_width, f32 render_height) {
+void render_init_shaders(u32 *shader_default, u32 *shader_batch, f32 render_width, f32 render_height) {
 	mat4x4 projection;
 
 	*shader_default = render_shader_create("./shaders/default.vert", "./shaders/default.frag");
+	*shader_batch = render_shader_create("./shaders/batch_quad.vert", "./shaders/batch_quad.frag");
 
 	mat4x4_ortho(projection, 0, render_width, 0, render_height, -2, 2);
 
@@ -56,6 +57,14 @@ void render_init_shaders(u32 *shader_default, f32 render_width, f32 render_heigh
 		GL_FALSE,
 		&projection[0][0]
 	);
+
+	glUseProgram(*shader_batch);
+	glUniformMatrix4fv(
+		glGetUniformLocation(*shader_batch, "projection"),
+		1,
+		GL_FALSE,
+		&projection[0][0]
+	);
 }
 
 void render_init_color_texture(u32 *texture) {
@@ -105,6 +114,41 @@ void render_init_quad(u32 *vao, u32 *vbo, u32 *ebo) {
 	glBindVertexArray(0);
 }
 
+void render_init_batch_quads(u32 *vao, u32 *vbo, u32 *ebo) {
+	glGenVertexArrays(1, vao);
+	glBindVertexArray(*vao);
+
+	u32 indices[MAX_BATCH_ELEMENTS];
+	for (u32 i = 0, offset = 0; i < MAX_BATCH_ELEMENTS; i += 6, offset += 4) {
+		indices[i + 0] = offset + 0;
+		indices[i + 1] = offset + 1;
+		indices[i + 2] = offset + 2;
+		indices[i + 3] = offset + 2;
+		indices[i + 4] = offset + 3;
+		indices[i + 5] = offset + 0;
+	}
+
+	glGenBuffers(1, vbo);
+	glBindBuffer(GL_ARRAY_BUFFER, *vbo);
+	glBufferData(GL_ARRAY_BUFFER, MAX_BATCH_VERTICES * sizeof(Batch_Vertex), NULL, GL_DYNAMIC_DRAW);
+
+	// [x, y], [u, v], [r, g, b, a]
+	glEnableVertexAttribArray(0);
+	glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(Batch_Vertex), (void*)offsetof(Batch_Vertex, position));
+	glEnableVertexAttribArray(1);
+	glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(Batch_Vertex), (void*)offsetof(Batch_Vertex, uvs));
+	glEnableVertexAttribArray(2);
+	glVertexAttribPointer(2, 4, GL_FLOAT, GL_FALSE, sizeof(Batch_Vertex), (void*)offsetof(Batch_Vertex, color));
+
+	glGenBuffers(1, ebo);
+	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, *ebo);
+	glBufferData(GL_ELEMENT_ARRAY_BUFFER, MAX_BATCH_ELEMENTS * sizeof(u32), indices, GL_STATIC_DRAW);
+
+	glBindVertexArray(0);
+	glBindBuffer(GL_ARRAY_BUFFER, 0);
+	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
+}
+
 void render_init_line(u32 *vao, u32 *vbo) {
 	glGenVertexArrays(1, vao);
 	glBindVertexArray(*vao);
diff --git a/src/engine/render/render_internal.h b/src/engine/render/render_internal.h
index ea15ab1..0bf77c0 100644
--- a/src/engine/render/render_internal.h
+++ b/src/engine/render/render_internal.h
@@ -7,8 +7,9 @@
 
 SDL_Window *render_init_window(u32 width, u32 height);
 void render_init_quad(u32 *vao, u32 *vbo, u32 *ebo);
+void render_init_batch_quads(u32 *vao, u32 *vbo, u32 *ebo);
 void render_init_color_texture(u32 *texture);
-void render_init_shaders(u32 *shader_default, f32 render_width, f32 render_height);
+void render_init_shaders(u32 *shader_default, u32 *shader_batch, f32 render_width, f32 render_height);
 void render_init_line(u32 *vao, u32 *vbo);
 u32 render_shader_create(const char *path_vert, const char *path_frag);
 
diff --git a/src/main.c b/src/main.c
index f341b32..861bd3d 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,6 +1,8 @@
+#include "engine/render.h"
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdbool.h>
+#include <time.h>
 #include <glad/glad.h>
 #define SDL_MAIN_HANDLED
 #include <SDL2/SDL.h>
@@ -72,6 +74,8 @@ void enemy_on_hit_static(Body *self, Static_Body *other, Hit hit) {
 }
 
 int main(int argc, char *argv[]) {
+	srand(time(NULL));
+
 	time_init(60);
 	config_init();
 	SDL_Window *window = render_init();
@@ -138,6 +142,15 @@ int main(int argc, char *argv[]) {
 		render_aabb((f32*)physics_body_get(entity_get(entity_a_id)->body_id), WHITE);
 		render_aabb((f32*)physics_body_get(entity_get(entity_b_id)->body_id), WHITE);
 
+		for (u32 i = 0; i < 10000; ++i) {
+			vec4 color = {
+				(rand() % 255) / 255.0,
+				(rand() % 255) / 255.0,
+				(rand() % 255) / 255.0,
+				(rand() % 255) / 255.0};
+			append_quad((vec2){rand() % 640, rand() % 360}, (vec2){rand() % 100, rand() % 100}, NULL, color);
+		}
+
 		render_end(window);
 
 		player_color[0] = 0;

From 598f6f17785b3012625e9bde78470061cc8727f1 Mon Sep 17 00:00:00 2001
From: Dylan Falconer <me@falconerd.com>
Date: Tue, 6 Sep 2022 17:28:07 +1000
Subject: [PATCH 7/7] sprite sheet rendering

---
 assets/player.png          | Bin 0 -> 5490 bytes
 src/engine/render.h        |  13 +++++++++-
 src/engine/render/render.c |  51 ++++++++++++++++++++++++++++++++++---
 src/main.c                 |  16 +++++-------
 4 files changed, 67 insertions(+), 13 deletions(-)
 create mode 100644 assets/player.png

diff --git a/assets/player.png b/assets/player.png
new file mode 100644
index 0000000000000000000000000000000000000000..88b57b23eabcada5d995b4be3e3aab48e6e66809
GIT binary patch
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diff --git a/src/engine/render.h b/src/engine/render.h
index cb149cb..7e7d8b6 100644
--- a/src/engine/render.h
+++ b/src/engine/render.h
@@ -11,18 +11,29 @@ typedef struct batch_vertex {
 	vec4 color;
 } Batch_Vertex;
 
+typedef struct sprite_sheet {
+	f32 width;
+	f32 height;
+	f32 cell_width;
+	f32 cell_height;
+	u32 texture_id;
+} Sprite_Sheet;
+
 #define MAX_BATCH_QUADS 10000
 #define MAX_BATCH_VERTICES 40000
 #define MAX_BATCH_ELEMENTS 60000
 
 SDL_Window *render_init(void);
 void render_begin(void);
-void render_end(SDL_Window *window);
+void render_end(SDL_Window *window, u32 batch_texture_id);
 void render_quad(vec2 pos, vec2 size, vec4 color);
 void render_quad_line(vec2 pos, vec2 size, vec4 color);
 void render_line_segment(vec2 start, vec2 end, vec4 color);
 void render_aabb(f32 *aabb, vec4 color);
 f32 render_get_scale();
 
+void render_sprite_sheet_init(Sprite_Sheet *sprite_sheet, const char *path, f32 cell_width, f32 cell_height);
+void render_sprite_sheet_frame(Sprite_Sheet *sprite_sheet, f32 row, f32 column, vec2 position);
+
 // Temporary!
 void append_quad(vec2 position, vec2 size, vec4 texture_coordinates, vec4 color);
diff --git a/src/engine/render/render.c b/src/engine/render/render.c
index 97b4568..f5a1a80 100644
--- a/src/engine/render/render.c
+++ b/src/engine/render/render.c
@@ -6,6 +6,7 @@
 #include "../global.h"
 #include "../render.h"
 #include "../array_list.h"
+#include "../util.h"
 #include "render_internal.h"
 
 static f32 window_width = 1920;
@@ -69,7 +70,7 @@ static void render_batch(Batch_Vertex *vertices, usize count, u32 texture_id) {
 	glDrawElements(GL_TRIANGLES, (count >> 2) * 6, GL_UNSIGNED_INT, NULL);
 }
 
-void append_quad(vec2 position, vec2 size, vec4 texture_coordinates, vec4 color) {
+static void append_quad(vec2 position, vec2 size, vec4 texture_coordinates, vec4 color) {
 	vec4 uvs = {0, 0, 1, 1};
 
 	if (texture_coordinates != NULL) {
@@ -101,8 +102,8 @@ void append_quad(vec2 position, vec2 size, vec4 texture_coordinates, vec4 color)
 	});
 }
 
-void render_end(SDL_Window *window) {
-	render_batch(list_batch->items, list_batch->len, texture_color);
+void render_end(SDL_Window *window, u32 batch_texture_id) {
+	render_batch(list_batch->items, list_batch->len, batch_texture_id);
 
 	SDL_GL_SwapWindow(window);
 }
@@ -171,6 +172,50 @@ void render_aabb(f32 *aabb, vec4 color) {
 	render_quad_line(&aabb[0], size, color);
 }
 
+static void calculate_sprite_texture_coordinates(vec4 result, f32 row, f32 column, f32 texture_width, f32 texture_height, f32 cell_width, f32 cell_height) {
+	f32 w = 1.0 / (texture_width / cell_width);
+	f32 h = 1.0 / (texture_height / cell_height);
+	f32 x = column * w;
+	f32 y = row * h;
+	result[0] = x;
+	result[1] = y;
+	result[2] = x + w;
+	result[3] = y + h;
+}
+
+void render_sprite_sheet_init(Sprite_Sheet *sprite_sheet, const char *path, f32 cell_width, f32 cell_height) {
+	glGenTextures(1, &sprite_sheet->texture_id);
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D, sprite_sheet->texture_id);
+
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);   
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+
+	int width, height, channel_count;
+	u8 *image_data = stbi_load(path, &width, &height, &channel_count, 0);
+	if (!image_data) {
+		ERROR_EXIT("Failed to load image: %s\n", path);
+	}
+	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, image_data);
+	stbi_image_free(image_data);
+
+	sprite_sheet->width = (f32)width;
+	sprite_sheet->height = (f32)height;
+	sprite_sheet->cell_width = cell_width;
+	sprite_sheet->cell_height = cell_height;
+}
+
+void render_sprite_sheet_frame(Sprite_Sheet *sprite_sheet, f32 row, f32 column, vec2 position) {
+	vec4 uvs;
+	calculate_sprite_texture_coordinates(uvs, row, column, sprite_sheet->width, sprite_sheet->height, sprite_sheet->cell_width, sprite_sheet->cell_height);
+
+	vec2 size = {sprite_sheet->cell_width, sprite_sheet->cell_height};
+	vec2 bottom_left = {position[0] - size[0] * 0.5, position[1] - size[1] * 0.5};
+	append_quad(bottom_left, size, uvs, (vec4){1, 1, 1, 1});
+}
+
 f32 render_get_scale() {
 	return scale;
 }
diff --git a/src/main.c b/src/main.c
index 861bd3d..7f67c2b 100644
--- a/src/main.c
+++ b/src/main.c
@@ -103,6 +103,9 @@ int main(int argc, char *argv[]) {
 	usize entity_a_id = entity_create((vec2){200, 200}, (vec2){25, 25}, (vec2){400, 0}, COLLISION_LAYER_ENEMY, enemy_mask, NULL, enemy_on_hit_static);
 	usize entity_b_id = entity_create((vec2){300, 300}, (vec2){25, 25}, (vec2){400, 0}, 0, enemy_mask, NULL, enemy_on_hit_static);
 
+	Sprite_Sheet sprite_sheet_player;
+	render_sprite_sheet_init(&sprite_sheet_player, "assets/player.png", 24, 24);
+
 	while (!should_quit) {
 		time_update();
 
@@ -142,16 +145,11 @@ int main(int argc, char *argv[]) {
 		render_aabb((f32*)physics_body_get(entity_get(entity_a_id)->body_id), WHITE);
 		render_aabb((f32*)physics_body_get(entity_get(entity_b_id)->body_id), WHITE);
 
-		for (u32 i = 0; i < 10000; ++i) {
-			vec4 color = {
-				(rand() % 255) / 255.0,
-				(rand() % 255) / 255.0,
-				(rand() % 255) / 255.0,
-				(rand() % 255) / 255.0};
-			append_quad((vec2){rand() % 640, rand() % 360}, (vec2){rand() % 100, rand() % 100}, NULL, color);
-		}
+		render_sprite_sheet_frame(&sprite_sheet_player, 1, 2, (vec2){100, 100});
+		render_sprite_sheet_frame(&sprite_sheet_player, 0, 4, (vec2){100, 200});
+		render_sprite_sheet_frame(&sprite_sheet_player, 0, 0, body_player->aabb.position);
 
-		render_end(window);
+		render_end(window, sprite_sheet_player.texture_id);
 
 		player_color[0] = 0;
 		player_color[2] = 1;