Some examples of equivalence of OpenGL math libraries glm (C++) and kazmath (C)

glm_kazmath.diff

--- p6.cpp	2014-03-28 22:55:37.000000000 -0500
+++ p6.c	2014-03-28 23:02:28.000000000 -0500
@@ -7,9 +7,8 @@
 #define PNG_DEBUG 3
 #include <png.h>
 
-#include <glm/glm.hpp>
-#include <glm/gtc/matrix_transform.hpp>
-#include <glm/gtc/type_ptr.hpp>
+#include <kazmath/kazmath.h>
+#define M_PI 3.14159265358979323846f
 
 #ifndef nullptr
   #define nullptr NULL
@@ -18,7 +17,7 @@
 
 // example of print_matrix usage:
 //
-// print_matrix(glm::value_ptr(model));
+// print_matrix(&model.mat[0]);
 //
 void print_matrix(const float * p_matrix)
 {
@@ -316,21 +315,24 @@
   free(image);
   glUniform1i(glGetUniformLocation(shaderProgram, "texPuppy"), 1);
 
-  glm::mat4 identity;
-  glm::mat4 model = glm::rotate(identity, 90.0f, glm::vec3(0.0f, 0.0f, 1.0f));
+  kmMat4 model;
+  kmMat4Identity(&model);
+  kmMat4RotationZ(&model, 90.0f * M_PI / 180.0f);
   GLint uniModel = glGetUniformLocation(shaderProgram, "model");
-  glUniformMatrix4fv(uniModel, 1, GL_FALSE, glm::value_ptr(model));
+  glUniformMatrix4fv(uniModel, 1, GL_FALSE, &model.mat[0]);
 
-  glm::mat4 view = glm::lookAt(
-      glm::vec3(1.2f, 1.2f, 1.2f),
-      glm::vec3(0.0f, 0.0f, 0.0f),
-      glm::vec3(0.0f, 0.0f, 1.0f));
+  kmMat4 view;
+  kmVec3 p_eye = { 1.2f, 1.2f, 1.2f };
+  kmVec3 p_ctr = { 0.0f, 0.0f, 0.0f };
+  kmVec3 p_up  = { 0.0f, 0.0f, 1.0f };
+  kmMat4LookAt(&view, &p_eye, &p_ctr, &p_up);
   GLint uniView = glGetUniformLocation(shaderProgram, "view");
-  glUniformMatrix4fv(uniView, 1, GL_FALSE, glm::value_ptr(view));
+  glUniformMatrix4fv(uniView, 1, GL_FALSE, &view.mat[0]);
 
-  glm::mat4 proj = glm::perspective(45.0f, 1280.0f / 720.0f, 1.0f, 10.0f);
+  kmMat4 proj;
+  kmMat4PerspectiveProjection(&proj, 45.0f, 1280.0f / 720.0f, 1.0f, 10.0f);
   GLint uniProj = glGetUniformLocation(shaderProgram, "proj");
-  glUniformMatrix4fv(uniProj, 1, GL_FALSE, glm::value_ptr(proj));
+  glUniformMatrix4fv(uniProj, 1, GL_FALSE, &proj.mat[0]);
 
   glEnable(GL_DEPTH_TEST);
   //glEnable(GL_STENCIL_TEST);
@@ -343,6 +345,8 @@
   //glStencilFunc(GL_EQUAL, 1, 0xFF);
   //glStencilMask(0x00);
 
+  kmMat4 tmp;
+
   GLint uniColor = glGetUniformLocation(shaderProgram, "overrideColor");
   while (!glfwWindowShouldClose(window)) {
     glfwPollEvents();
@@ -351,9 +355,9 @@
 
     glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-    model = glm::rotate(identity, (float)clock() / (float)CLOCKS_PER_SEC * 90.0f,
-        glm::vec3(0.0f, 0.0f, 1.0f));
-    glUniformMatrix4fv(uniModel, 1, GL_FALSE, glm::value_ptr(model));
+    kmMat4Identity(&model);
+    kmMat4RotationZ(&model, (float)clock() / (float)CLOCKS_PER_SEC * 90.0f * M_PI / 180.0f);
+    glUniformMatrix4fv(uniModel, 1, GL_FALSE, &model.mat[0]);
     //glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
     glDrawArrays(GL_TRIANGLES, 0, 36);
 
@@ -373,8 +377,11 @@
       glStencilMask(0x00);
       glDepthMask(GL_TRUE);
 
-      model = glm::scale(glm::translate(model, glm::vec3(0, 0, -1)), glm::vec3(1, 1, -1));
-      glUniformMatrix4fv(uniModel, 1, GL_FALSE, glm::value_ptr(model));
+      kmMat4Translation(&tmp, 0.0f, 0.0f, -1.0f);
+      kmMat4Multiply(&model, &model, &tmp);
+      kmMat4Scaling(&tmp, 1.0f, 1.0f, -1.0f);
+      kmMat4Multiply(&model, &model, &tmp);
+      glUniformMatrix4fv(uniModel, 1, GL_FALSE, &model.mat[0]);
       glUniform3f(uniColor, 0.3f, 0.3f, 0.3f);
       glDrawArrays(GL_TRIANGLES, 0, 36);
       glUniform3f(uniColor, 1.0f, 1.0f, 1.0f);