redo look-at, test cube with lines

src/main.c

@@ -136,14 +136,14 @@ void init(void) {
 
 	GLfloat vertices[] = {
 		// X  // Y
-		-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,
+		 1.0f,  1.0f,  1.0f,
+		 1.0f,  1.0f, -1.0f,
+		 1.0f, -1.0f,  1.0f,
+		 1.0f, -1.0f, -1.0f,
+		-1.0f,  1.0f,  1.0f,
+		-1.0f,  1.0f, -1.0f,
+		-1.0f, -1.0f,  1.0f,
+		-1.0f, -1.0f, -1.0f,
 	};
 
 	GLuint restart = 128;
@@ -151,8 +151,24 @@ void init(void) {
 	glPrimitiveRestartIndex(restart);
 
 	GLuint indices[] = {
-		0, 1, 2,
-		0, 2, 5
+		0, 1,
+		0, 2,
+		0, 4,
+
+		1, 3,
+		1, 5,
+
+		2, 3,
+		2, 6,
+
+		3, 7,
+
+		4, 5,
+		4, 6,
+
+		5, 7,
+
+		6, 7
 	};
 
 	DEBUG("Creating vertext buffer");
@@ -204,23 +220,26 @@ GLfloat currentHue = 0.0f;
 void draw(void) {
 	updateStatusDisplay();
 
-	currentHue += 0.005f;
+	currentHue += 0.0005f;
 	if (currentHue > 1.0) currentHue = 0.0f;
 
 	glClear(GL_COLOR_BUFFER_BIT);
 	glUseProgram(program);
 
 	mat4 transformMatrix;
-	vec3 position = {0.5f, 0.5f, 0.0f};
+	vec3 scale = {0.2f, 0.2f, 0.2f};
 	mat4Identity(transformMatrix);
-	// mat4RotateZ(transformMatrix, transformMatrix, currentHue * PI * 2);
-	// mat4RotateY(transformMatrix, transformMatrix, currentHue * PI * 2);
+	mat4Scale(transformMatrix, transformMatrix, scale);
+	
+	mat4RotateZ(transformMatrix, transformMatrix, currentHue * PI * 2);
+	mat4RotateY(transformMatrix, transformMatrix, currentHue * PI * 2);
 
 	mat4 viewMatrix;
+	mat4Identity(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);
+	// mat4BuildLookAt(viewMatrix, cameraPos, cameraLookAt, cameraUp);
 
 	GLuint transformLocation = glGetUniformLocation(program, "uTransform");
 	glUniformMatrix4fv(transformLocation, 1, GL_FALSE, transformMatrix);
@@ -230,7 +249,7 @@ void draw(void) {
 
 	glBindVertexArray(vertexArrayObject);
 	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer);
-	glDrawElements(GL_TRIANGLES, 20, GL_UNSIGNED_INT, 0);
+	glDrawElements(GL_LINES, 24, GL_UNSIGNED_INT, 0);
 }
 
 void framebuffer_size_callback(GLFWwindow* window, int width, int height) {

src/matrix-math.c

@@ -76,6 +76,18 @@ void mat4Translate(mat4 out, mat4 in, vec3 v) {
 
 	mat4Multiply(out, T, in);
 }
+
+void mat4Scale(mat4 out, mat4 in, vec3 v) {
+	mat4 T;
+	mat4Identity(T);
+
+	T[0] = v[0];
+	T[5] = v[1];
+	T[10] = v[2];
+
+	mat4Multiply(out, T, in);
+}
+
 void mat4RotateX(mat4 out, mat4 in, GLfloat a) {
 	mat4 T;
 	mat4Identity(T);
@@ -130,42 +142,42 @@ void vec3CrossProduct(vec3 out, vec3 a, vec3 b) {
 }
 
 void vec3Normalise(vec3 out, vec3 in) {
-	GLfloat length = sqrt(in[0] * in[0] + in[1] * in[1] + in[2] * in[2]);
+	GLfloat length = vec3Length(in);
 	out[0] = in[0] / length;
 	out[1] = in[1] / length;
 	out[2] = in[2] / length;
 }
 
+GLfloat vec3Length(vec3 in) {
+	return sqrt(in[0] * in[0] + in[1] * in[1] + in[2] * in[2]);
+}
+
 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) {
+void mat4BuildLookAt(mat4 out, vec3 eye, vec3 look, vec3 up) {
 	vec3 n;
 	vec3 u;
 	vec3 v;
+	vec3 t;
 
-	vec3Subtract(n, eye, center);
+	vec3Subtract(n, eye, look);
 
 	vec3CrossProduct(u, up, n);
 
 	vec3CrossProduct(v, n, u);
 
-	mat4Identity(out);
+	vec3Normalise(n, n);
+	vec3Normalise(u, u);
+	vec3Normalise(v, v);
 
-	out[0] = u[0];
-	out[1] = v[0];
-	out[2] = n[0];
+	t[0] = - vec3DotProduct(u, eye);
+	t[1] = - vec3DotProduct(v, eye);
+	t[2] = - vec3DotProduct(n, eye);
 
-	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);
+	out[0] = u[0]; out[4] = u[1]; out[8]  = u[2]; out[12] = t[0];
+	out[1] = v[0]; out[5] = v[1]; out[9]  = v[2]; out[13] = t[1];
+	out[2] = n[0]; out[6] = n[1]; out[10] = n[2]; out[14] = t[2];
+	out[3] = 0;    out[7] = 0;    out[11] = 0;    out[15] = 1;
 }

src/matrix-math.h

@@ -18,10 +18,17 @@ 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 mat4Scale(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);
 
+extern void vec3Subtract(vec3 out, vec3 a, vec3 b);
+extern void vec3CrossProduct(vec3 out, vec3 a, vec3 b);
+extern void vec3Normalise(vec3 out, vec3 in);
+extern GLfloat vec3Length(vec3 in);
+extern GLfloat vec3DotProduct(vec3 a, vec3 b);
+
 #endif