From 2cbe37fb57c2e223a78caebe37e2f5abc9216487 Mon Sep 17 00:00:00 2001
From: Leo Tenenbaum <pommicket@gmail.com>
Date: Fri, 26 Feb 2021 15:27:53 -0500
Subject: perlin noise

---
 01f.glsl | 36 ++++++++++++++++++++++++++++++++++++
 01v.glsl |  9 +++++++++
 gl.c     |  4 ++--
 main.c   | 16 ++++++++++++----
 4 files changed, 59 insertions(+), 6 deletions(-)
 create mode 100644 01f.glsl
 create mode 100644 01v.glsl

diff --git a/01f.glsl b/01f.glsl
new file mode 100644
index 0000000..9baa911
--- /dev/null
+++ b/01f.glsl
@@ -0,0 +1,36 @@
+varying vec2 pos;
+uniform float u_aspect_ratio;
+
+vec2 rand(vec2 co) {
+    float random = 2920.0 * sin(co.x * 21942.0 + co.y * 171324.0 + 8912.0) * cos(co.x * 23157.0 * co.y * 217832.0 + 9758.0);
+    return vec2(cos(random), sin(random));
+}
+
+float dot_grid_gradient(vec2 floor_p, vec2 p) {
+	vec2 gradient = rand(floor_p);
+	vec2 dist = p - floor_p;
+	return dot(dist, gradient);
+}
+
+void main() {
+	vec2 p = pos * 10.0;
+	p.x *= u_aspect_ratio;
+	vec2 p0 = floor(p);
+	vec2 p1 = p0 + vec2(1.0, 1.0);
+	vec2 weight = p - p0;
+	weight = smoothstep(0.0, 1.0, weight);
+	
+	float n0 = dot_grid_gradient(vec2(p0.x, p0.y), p);
+	float n1 = dot_grid_gradient(vec2(p1.x, p0.y), p);
+	float ix0 = mix(n0, n1, weight.x);
+		
+	n0 = dot_grid_gradient(vec2(p0.x, p1.y), p);
+	n1 = dot_grid_gradient(vec2(p1.x, p1.y), p);
+	float ix1 = mix(n0, n1, weight.x);
+	
+	float v = mix(ix0, ix1, weight.y);
+	v += 1.0;
+	v *= 0.5;
+	vec3 color = mix(vec3(0.4, 0.2, 1.0), vec3(1.0, 0.6, 0.6), v);
+	gl_FragColor = vec4(color, 1.0);
+}
diff --git a/01v.glsl b/01v.glsl
new file mode 100644
index 0000000..d5286df
--- /dev/null
+++ b/01v.glsl
@@ -0,0 +1,9 @@
+attribute vec2 v_render_pos;
+attribute vec2 v_pos;
+
+varying vec2 pos;
+
+void main() {
+	gl_Position = vec4(v_render_pos, 0.0, 1.0);
+	pos = v_pos;
+}
diff --git a/gl.c b/gl.c
index 0fb89ef..00be97a 100644
--- a/gl.c
+++ b/gl.c
@@ -131,7 +131,7 @@ static GLuint gl_compile_and_link_shaders(char const *vshader_code, char const *
 static GLuint gl_attrib_loc(GLuint program, char const *attrib) {
 	GLint loc = glGetAttribLocation(program, attrib);
 	if (loc == -1) {
-		debug_print("Couldn't find vertex attribute %s.\n", attrib);
+		//debug_print("Couldn't find vertex attribute %s.\n", attrib);
 		return (GLuint)-1;
 	}
 	return (GLuint)loc;
@@ -140,7 +140,7 @@ static GLuint gl_attrib_loc(GLuint program, char const *attrib) {
 static GLint gl_uniform_loc(GLuint program, char const *uniform) {
 	GLint loc = glGetUniformLocation(program, uniform);
 	if (loc == -1) {
-		debug_print("Couldn't find uniform: %s.\n", uniform);
+		//debug_print("Couldn't find uniform: %s.\n", uniform);
 		return -1;
 	}
 	return loc;
diff --git a/main.c b/main.c
index 705c699..8ba68c8 100644
--- a/main.c
+++ b/main.c
@@ -88,9 +88,11 @@ static void shader_check_for_changes(Shader *shader) {
 }
 
 static double start_time;
+static float window_width, window_height;
 
 static void shader_draw(Shader *shader, Rect where) {
 	shader_check_for_changes(shader);
+	if (!shader->program) return;
 	float x1, y1, x2, y2;
 	rect_coords(where, &x1, &y1, &x2, &y2);
 	
@@ -132,6 +134,9 @@ static void shader_draw(Shader *shader, Rect where) {
 	GLint u_time = gl_uniform_loc(shader->program, "u_time");
 	if (u_time >= 0)
 		glUniform1f(u_time, (float)fmod(time_get_seconds() - start_time, 10000));
+	GLint u_aspect_ratio = gl_uniform_loc(shader->program, "u_aspect_ratio");
+	if (u_aspect_ratio >= 0)
+		glUniform1f(u_aspect_ratio, window_width / window_height);
 	glDrawArrays(GL_TRIANGLES, 0, 6);	
 }
 
@@ -241,9 +246,12 @@ int main(void) {
 	bool quit = false, fullscreen = false;
 	start_time = time_get_seconds();
 	while (!quit) {
+	int iwindow_width, iwindow_height;
+		SDL_GetWindowSize(window, &iwindow_width, &iwindow_height);
+		window_width = (float)iwindow_width;
+		window_height = (float)iwindow_height;
+		
 		SDL_Event event = {0};
-		int window_width, window_height;
-		SDL_GetWindowSize(window, &window_width, &window_height);
 		v2 *mouse_clicks = NULL;
 		while (SDL_PollEvent(&event)) {
 			switch (event.type) {
@@ -251,8 +259,8 @@ int main(void) {
 				quit = true;
 				break;
 			case SDL_MOUSEBUTTONDOWN: {
-				float x = -1 + 2 * (float)event.button.x / (float)window_width;
-				float y = +1 - 2 * (float)event.button.y / (float)window_height;
+				float x = -1 + 2 * (float)event.button.x / window_width;
+				float y = +1 - 2 * (float)event.button.y / window_height;
 				arr_add(mouse_clicks, V2(x, y));
 			} break;
 			case SDL_KEYDOWN:
-- 
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