u02

src/main.c

@@ -1,5 +1,6 @@
 #include <GL/glew.h>
 #include <GLFW/glfw3.h>
+#include <math.h>
 #include <stdio.h>
 #include <string.h>
 #include <time.h>
@@ -21,6 +22,40 @@ GLuint initialWindowHeight = 600;
 int frameCount = 0;
 struct timespec last_time, current_time;
 
+typedef struct ColorRGB {
+	GLfloat r;
+	GLfloat g;
+	GLfloat b;
+} ColorRGB;
+
+// Color Conversion Functions from https://gist.github.com/ciembor/1494530
+GLfloat hueToRgb(GLfloat p, GLfloat q, GLfloat t) {
+	if (t < 0) t += 1;
+	if (t > 1) t -= 1;
+	if (t < 1./6) return p + (q - p) * 6 * t;
+	if (t < 1./2) return q;
+	if (t < 2./3) return p + (q - p) * (2./3 - t) * 6;
+	
+  return p;
+}
+
+// Color Conversion Functions by Copilot
+ColorRGB hslToRgb(GLfloat h, GLfloat s, GLfloat l) {
+	ColorRGB result = {0, 0, 0};
+
+	if(0 == s) {
+		result.r = result.g = result.b = l; // achromatic
+	} else {
+		float q = l < 0.5 ? l * (1 + s) : l + s - l * s;
+		float p = 2 * l - q;
+		result.r = hueToRgb(p, q, h + 1./3);
+		result.g = hueToRgb(p, q, h);
+		result.b = hueToRgb(p, q, h - 1./3);
+	}
+
+	return result;
+}
+
 void initialiseStatusDisplay() {
 	clock_gettime(CLOCK_MONOTONIC, &last_time);
 }
@@ -72,19 +107,72 @@ void init(void) {
 	INFO("Shader Program Done.");
 
 	// create triangle buffer
-	GLfloat triangleVertices[] =
-	{
-		 //X     //Y    // R  //G   /B
-		 0.0f,  0.5f,   0.0f, 1.0f, 1.0f,
-		-0.5f, -0.5f,   1.0f, 0.0f, 1.0f,
-		 0.5f, -0.5f,   1.0f, 1.0f, 0.0f
+	/**
+	 * -0.35              0.35
+	 * |     -0.2    0.2  |
+	 * |    |        |    |
+	 * 
+	 * +----+        +----+    ---  0.6
+	 * |    |        |    |    
+	 * |    |        |    |
+	 * |    +--------+    |    ---  0.1
+	 * |                  |
+	 * |    +--------+    |    --- -0.1
+	 * |    |        |    |
+	 * |    |        |    |
+	 * +----+        +----+    --- -0.6
+	 *
+	 * +------------------+    --- -0.7
+	 * |                  |
+	 * +------------------+    --- -0.9
+	 *   
+	 */    
+
+	GLfloat vertices[] = {
+		// X  // Y
+
+		// left vertical bar
+		-0.35f, -0.6f,
+		-0.35f, 0.6f,
+		-0.2f, 0.6f,
+
+		-0.35f, -0.6f,
+		-0.2f, 0.6f,
+		-0.2f, -0.6f,
+
+		// right vertical bar
+		0.35f, -0.6f,
+		0.35f, 0.6f,
+		0.2f, 0.6f,
+
+		0.35f, -0.6f,
+		0.2f, 0.6f,
+		0.2f, -0.6f,
+
+		// middle bar
+		-0.2f, -0.1f,
+		-0.2f, 0.1f,
+		0.2f, 0.1f,
+
+		-0.2f, -0.1f,
+		0.2f, 0.1f,
+		0.2f, -0.1f,
+
+		// bottom bar
+		-0.35f, -0.7f,
+		-0.35f, -0.9f,
+		0.35f, -0.9f,
+
+		-0.35f, -0.7f,
+		0.35f, -0.9f,
+		0.35f, -0.7f
 	};
 
 	DEBUG("Creating vertext buffer");
 	GLuint vertexBuffer;
 	glGenBuffers(1, &vertexBuffer);
 	glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
-	glBufferData(GL_ARRAY_BUFFER, sizeof(triangleVertices), triangleVertices, GL_STATIC_DRAW);
+	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
 	glBindBuffer(GL_ARRAY_BUFFER, 0);
 
 	DEBUG("Creating vertex array object");
@@ -99,15 +187,11 @@ void init(void) {
 		2, // number of values to read
 		GL_FLOAT, // type of value
 		GL_FALSE, // if values are normalised
-		5 * sizeof(GLfloat), // stride - distance between vertices
+		2 * sizeof(GLfloat), // stride - distance between vertices
 		0 // start offset
 	);
 	glEnableVertexAttribArray(0);
 
-	// vertex color data
-	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), (GLvoid*)(2 * sizeof(GLfloat)));
-	glEnableVertexAttribArray(1);
-
 	glBindBuffer(GL_ARRAY_BUFFER, 0);
 	glBindVertexArray(0);
 
@@ -119,13 +203,26 @@ void init(void) {
 	INFO("--- Initialisation done ---");
 }
 
+GLfloat currentHue = 0.0f;
+
 void draw(void) {
 	updateStatusDisplay();
+
+	currentHue += 0.001f;
+	if (currentHue > 1.0) currentHue = 0.0f;
+
 	glClear(GL_COLOR_BUFFER_BIT);
 	glUseProgram(program);
 
+	GLuint colorLocation = glGetUniformLocation(program, "uColor");
+	ColorRGB color = hslToRgb(currentHue, 1.0f, 0.5f);
+	glUniform3f(colorLocation, color.r, color.g, color.b);
+
+	GLuint positionLocation = glGetUniformLocation(program, "uPosition");
+	glUniform2f(positionLocation, cos(currentHue * 2 * M_PI) * 0.2f, sin(currentHue * 2 * M_PI) * 0.2f);
+
 	glBindVertexArray(vertexArrayObject);
-	glDrawArrays(GL_TRIANGLES, 0, 3);
+	glDrawArrays(GL_TRIANGLES, 0, 48);
 }
 
 void framebuffer_size_callback(GLFWwindow* window, int width, int height) {

src/shaders/vertex.glsl

@@ -1,10 +1,11 @@
 #version 330 core
 layout (location = 0) in vec2 aPosition;
-layout (location = 1) in vec3 aColor;
+uniform vec3 uColor;
+uniform vec2 uPosition;
 
 out vec3 vertexColor;
 
 void main() {
-	vertexColor = aColor;
-	gl_Position = vec4(aPosition, 0.0, 1.0);
+	vertexColor = uColor;
+	gl_Position = vec4(uPosition + aPosition, 0.0, 1.0);
 }