polyadvent

commit eb690f959926b81ba79e3554d295df129598d087
parent 80d81f1133d46c8243abf01ea393bb5a71e3b06b
Author: William Casarin <jb55@jb55.com>
Date:   Fri, 26 Oct 2018 23:55:35 -0700

ortho camera. will need for UI

Diffstat:
M
src/mat4.c
 | 
29
++++++++++++++++++++++++++++-
M
src/mat4.h
 | 
3
+++

2 files changed, 31 insertions(+), 1 deletion(-)
diff --git a/src/mat4.c b/src/mat4.c
@@ -151,12 +151,39 @@ mat4 *mat4_translate (mat4 *mat, float *v3, mat4 *dest) {
 }
 
 mat4 *mat4_perspective(float fov, float aspect, float near,
-                       float far, mat4 *dest) {
+                       float far, mat4 *dest)
+{
 	float top = near * tanf(fov*PI / 360.0f);
 	float right = top * aspect;
 	return mat4_frustum(-right, right, -top, top, near, far, dest);
 }
 
+mat4 *mat4_ortho(float left, float right, float bottom, float top, float near,
+            float far, mat4 *dest)
+{
+    float lr = 1.0 / (left - right);
+    float bt = 1.0 / (bottom - top);
+    float nf = 1.0 / (near - far);
+    dest[0] = -2 * lr;
+    dest[1] = 0;
+    dest[2] = 0;
+    dest[3] = 0;
+    dest[4] = 0;
+    dest[5] = -2 * bt;
+    dest[6] = 0;
+    dest[7] = 0;
+    dest[8] = 0;
+    dest[9] = 0;
+    dest[10] = 2 * nf;
+    dest[11] = 0;
+    dest[12] = (left + right) * lr;
+    dest[13] = (top + bottom) * bt;
+    dest[14] = (far + near) * nf;
+    dest[15] = 1;
+    return dest;
+}
+
+
 mat4 *mat4_inverse(mat4 *src, mat4 *dest) {
 	if(dest == NULL) { dest = src; }
 
diff --git a/src/mat4.h b/src/mat4.h
@@ -14,6 +14,9 @@ mat4 *mat4_frustum (float left, float right, float bottom,
 mat4 *mat4_perspective(float fov, float aspect, float near,
                        float far, mat4 *dest);
 
+mat4 *mat4_ortho(float left, float right, float bottom, float top, float near,
+                 float far, mat4 *dest);
+
 mat4 *mat4_translate (mat4 *mat, float *vec3, mat4 *dest);
 mat4 *mat4_transpose(mat4 *src, mat4 *dest);
 mat4 *mat4_inverse(mat4 *src, mat4 *dest);