work in progress

src/main.c

@@ -13,6 +13,7 @@
 #include "matrix-math.h"
 
 #define STATUS_INTERVAL 0.5
+#define PI 3.14159f
 
 GLuint program;
 
@@ -80,15 +81,6 @@ void updateStatusDisplay() {
 
 void init(void) {
 
-	mat4 t = {
-		1, 2, 3, 4,
-		5, 6, 7, 8,
-		9, 10, 11, 12,
-		13, 14, 15, 16
-	};
-
-	mat4Print(t);
-
 	INFO("Compiling Shaders...");
 
 	// create and compile vertex shader
@@ -144,23 +136,14 @@ void init(void) {
 
 	GLfloat vertices[] = {
 		// X  // Y
-		-0.35f, 0.6f,
-		-0.2f, 0.6f,
-		-0.2f, 0.1f,
-		0.2f, 0.1f,
-		0.2f, 0.6f,
-		0.35f, 0.6f,
-		0.35f, -0.6f,
-		0.2f, -0.6f,
-		0.2f, -0.1f,
-		-0.2f, -0.1f,
-		-0.2f, -0.6f,
-		-0.35f, -0.6f,
-
-		-0.35f, -0.7f,
-		0.35f, -0.7f,
-		0.35f, -0.9f,
-		-0.35f, -0.9f
+		-0.5f, -0.5f, -0.5f,
+		-0.5f, -0.5f,  0.5f,
+		-0.5f,  0.5f, -0.5f,
+		-0.5f,  0.5f,  0.5f,
+		 0.5f, -0.5f, -0.5f,
+		 0.5f, -0.5f,  0.5f,
+		 0.5f,  0.5f, -0.5f,
+		 0.5f,  0.5f,  0.5f,
 	};
 
 	GLuint restart = 128;
@@ -168,10 +151,8 @@ void init(void) {
 	glPrimitiveRestartIndex(restart);
 
 	GLuint indices[] = {
-		1, 0, 10, 11, restart,
-		2, 9, 3, 8, restart,
-		5, 4, 6, 7, restart,
-		12, 15, 13, 14, restart
+		0, 1, 2,
+		0, 2, 5
 	};
 
 	DEBUG("Creating vertext buffer");
@@ -190,10 +171,10 @@ void init(void) {
 	// vertex position data
 	glVertexAttribPointer(
 		0, // shader location
-		2, // number of values to read
+		3, // number of values to read
 		GL_FLOAT, // type of value
 		GL_FALSE, // if values are normalised
-		2 * sizeof(GLfloat), // stride - distance between vertices
+		3 * sizeof(GLfloat), // stride - distance between vertices
 		0 // start offset
 	);
 	glEnableVertexAttribArray(0);
@@ -210,7 +191,7 @@ void init(void) {
 	glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
 	glViewport(0, 0, initialWindowWidth, initialWindowHeight);
 
-	glEnable(GL_CULL_FACE);
+	// glEnable(GL_CULL_FACE);
 	glFrontFace(GL_CCW);
 
 	initialiseStatusDisplay();
@@ -223,18 +204,33 @@ GLfloat currentHue = 0.0f;
 void draw(void) {
 	updateStatusDisplay();
 
-	currentHue += 0.001f;
+	currentHue += 0.005f;
 	if (currentHue > 1.0) currentHue = 0.0f;
 
 	glClear(GL_COLOR_BUFFER_BIT);
 	glUseProgram(program);
 
-	GLuint positionLocation = glGetUniformLocation(program, "uPosition");
-	glUniform2f(positionLocation, cos(currentHue * 2 * M_PI) * 0.2f, sin(currentHue * 2 * M_PI) * 0.2f);
+	mat4 transformMatrix;
+	vec3 position = {0.5f, 0.5f, 0.0f};
+	mat4Identity(transformMatrix);
+	// mat4RotateZ(transformMatrix, transformMatrix, currentHue * PI * 2);
+	// mat4RotateY(transformMatrix, transformMatrix, currentHue * PI * 2);
+
+	mat4 viewMatrix;
+	vec3 cameraPos = {0.0f, sin(currentHue * PI * 2), 0.0f};
+	vec3 cameraLookAt = {0.0f, 0.0f, -1.0f};
+	vec3 cameraUp = {0.0f, 1.0f, 0.0f};
+	mat4BuildLookAt(viewMatrix, cameraPos, cameraLookAt, cameraUp);
+
+	GLuint transformLocation = glGetUniformLocation(program, "uTransform");
+	glUniformMatrix4fv(transformLocation, 1, GL_FALSE, transformMatrix);
+
+	GLuint viewLocation = glGetUniformLocation(program, "uView");
+	glUniformMatrix4fv(viewLocation, 1, GL_FALSE, viewMatrix);
 
 	glBindVertexArray(vertexArrayObject);
 	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer);
-	glDrawElements(GL_TRIANGLE_STRIP, 20, GL_UNSIGNED_INT, 0);
+	glDrawElements(GL_TRIANGLES, 20, GL_UNSIGNED_INT, 0);
 }
 
 void framebuffer_size_callback(GLFWwindow* window, int width, int height) {

src/matrix-math.c

@@ -64,4 +64,108 @@ void mat4Print(mat4 m) {
 		}
 		printf("\n");
 	}
+}
+
+void mat4Translate(mat4 out, mat4 in, vec3 v) {
+	mat4 T;
+	mat4Identity(T);
+	
+	T[12] = v[0];
+	T[13] = v[1];
+	T[14] = v[2];
+
+	mat4Multiply(out, T, in);
+}
+void mat4RotateX(mat4 out, mat4 in, GLfloat a) {
+	mat4 T;
+	mat4Identity(T);
+
+	T[5] = cos(a);
+	T[6] = sin(a);
+	T[9] = -sin(a);
+	T[10] = cos(a);
+	
+	mat4Multiply(out, T, in);
+}
+
+void mat4RotateY(mat4 out, mat4 in, GLfloat a) {
+	mat4 T;
+	mat4Identity(T);
+
+	T[0] = cos(a);
+	T[2] = -sin(a);
+	T[8] = sin(a);
+	T[10] = cos(a);
+	
+	mat4Multiply(out, T, in);
+}
+
+void mat4RotateZ(mat4 out, mat4 in, GLfloat a) {
+	mat4 T;
+	mat4Identity(T);
+
+	T[0] = cos(a);
+	T[1] = sin(a);
+	T[4] = -sin(a);
+	T[5] = cos(a);
+
+	mat4Multiply(out, T, in);
+}
+
+void vec3Subtract(vec3 out, vec3 a, vec3 b) {
+	out[0] = a[0] - b[0];
+	out[1] = a[1] - b[1];
+	out[2] = a[2] - b[2];
+}
+
+void vec3CrossProduct(vec3 out, vec3 a, vec3 b) {
+	vec3 result;
+	result[0] = a[1] * b[2] - a[2] * b[1];
+	result[1] = a[2] * b[0] - a[0] * b[2];
+	result[2] = a[0] * b[1] - a[1] * b[0];
+
+	out[0] = result[0];
+	out[1] = result[1];
+	out[2] = result[2];
+}
+
+void vec3Normalise(vec3 out, vec3 in) {
+	GLfloat length = sqrt(in[0] * in[0] + in[1] * in[1] + in[2] * in[2]);
+	out[0] = in[0] / length;
+	out[1] = in[1] / length;
+	out[2] = in[2] / length;
+}
+
+GLfloat vec3DotProduct(vec3 a, vec3 b) {
+	return a[0] * b[0] + a[1] * b[1] + a[2] * b[2];
+}
+
+void mat4BuildLookAt(mat4 out, vec3 eye, vec3 center, vec3 up) {
+	vec3 n;
+	vec3 u;
+	vec3 v;
+
+	vec3Subtract(n, eye, center);
+
+	vec3CrossProduct(u, up, n);
+
+	vec3CrossProduct(v, n, u);
+
+	mat4Identity(out);
+
+	out[0] = u[0];
+	out[1] = v[0];
+	out[2] = n[0];
+
+	out[4] = u[1];
+	out[5] = v[1];
+	out[6] = n[1];
+
+	out[8] = u[2];
+	out[9] = v[2];
+	out[10] = n[2];
+
+	out[12] = - vec3DotProduct(u, eye);
+	out[13] = - vec3DotProduct(v, eye);
+	out[14] = - vec3DotProduct(n, eye);
 }

src/matrix-math.h

@@ -1,16 +1,14 @@
 #ifndef MATRIX_MATH_H
 #define MATRIX_MATH_H
 
-#include <GL/gl.h>	
-
-// TODO: figure out better type definition to avoid constant casting to GLfloat*
-// possibly typedef float mat4[16];
+#include <GL/gl.h>
 
 /**
  * !!! ALL matrices are in column major
  */
 
 typedef GLfloat vec4[4];
+typedef GLfloat vec3[3];
 
 typedef GLfloat mat4[16];
 
@@ -19,5 +17,11 @@ extern void mat4Copy(mat4 src, mat4 dst);
 extern void mat4Empty(mat4 mat);
 extern void mat4Multiply(mat4 result, mat4 A, mat4 B);
 extern void mat4Print(mat4 m);
+extern void mat4Translate(mat4 out, mat4 in, vec3 v);
+extern void mat4RotateX(mat4 out, mat4 in, GLfloat a);
+extern void mat4RotateY(mat4 out, mat4 in, GLfloat a);
+extern void mat4RotateZ(mat4 out, mat4 in, GLfloat a);
+extern void mat4BuildLookAt(mat4 out, vec3 eye, vec3 center, vec3 up);
+extern void mat4BuildProjection(mat4 out, GLfloat r, GLfloat l, GLfloat t, GLfloat b, GLfloat f, GLfloat n);
 
 #endif

src/shaders/vertex.glsl

@@ -1,10 +1,11 @@
 #version 330 core
-layout (location = 0) in vec2 aPosition;
-uniform vec2 uPosition;
+layout (location = 0) in vec3 aPosition;
+uniform mat4 uTransform;
+uniform mat4 uView;
 
 out vec3 vertexColor;
 
 void main() {
 	vertexColor = vec3(1.0, 0.1, 0.1);
-	gl_Position = vec4(uPosition + aPosition, 0.0, 1.0);
+	gl_Position = uView * uTransform * vec4(aPosition, 1.0);
 }