opengl

commit db1e273b0daac9440c21c78d35c684c703cab174
parent b4090b3e06d99d4c36aaef09c240423f720e15cf
Author: Matsuda Kenji <info@mtkn.jp>
Date:   Tue, 27 Jun 2023 18:49:42 +0900

add rotation around arbitrary axis

Diffstat:
M
glm.c
 | 
19
+++++++++++++------
M
main.c
 | 
3
+--

2 files changed, 14 insertions(+), 8 deletions(-)
diff --git a/glm.c b/glm.c
@@ -154,16 +154,23 @@ translate(mat *m, const vec *v)
 	return NULL;
 }
 
-
-// TODO: implementation in progress. use arbitrary axis.
 mat *
 rotate(mat *m, float rad, vec *axis)
 {
+	if (axis->size != 3) {
+		assert(!"axis size must be 3");
+	}
+	float x = axis->data[0];
+	float y = axis->data[1];
+	float z = axis->data[2];
+	float c = cosf(rad);
+	float s = sinf(rad);
 	mat *rot = matMake((float[]){ // column major...
-		cos(rad), sin(rad), 0, 0,
-		-sin(rad), cos(rad), 0, 0,
-		0, 0, 1, 0,
-		0, 0, 0, 1}, 4);
+		c+x*x*(1-c),   y*x*(1-c)+z*s, z*x*(1-c)-y*s, 0, 
+		x*y*(1-c)-z*s, c+y*y*(1-c),   z*y*(1-c)+x*s, 0, 
+		x*z*(1-c)+y*s, y*z*(1-c)-x*s, c+z*z*(1-c),   0, 
+		0,             0,             0,             1, 
+		}, 4);
 	matDot(m, rot);
 	matFree(rot);
 	return m;
diff --git a/main.c b/main.c
@@ -50,7 +50,6 @@ processInput(GLFWwindow *window)
 int
 main(void)
 {
-	float theta = 0;
 	float delta = 0.01;
 	float vertices[] = {
 		// positions,    texture coords
@@ -67,7 +66,7 @@ main(void)
 		0.0, 1.0, 0.0, 0.0,
 		0.0, 0.0, 1.0, 0.0,
 		0.0, 0.0, 0.0, 1.0,}, 4);
-	vec *axis = vecMake((float[]){0.0, 0.0, 1.0}, 3);
+	vec *axis = vecMake((float[]){1.0, 0.0, 0.0}, 3);
 	
 	// initialize glfw
 	glfwInit();