load and compile shaders

template/f_shader.glsl

@@ -0,0 +1,4 @@
+
+void main(void)
+{
+}

template/test.cc

@@ -1,14 +1,87 @@
 
+#define GL_GLEXT_PROTOTYPES
+#include <sys/stat.h>
 #include <SDL/SDL.h>
 #include <GL/gl.h>
 #include <GL/glu.h>
+#include <iostream>
+
+using namespace std;
 
 #define WIDTH   800
 #define HEIGHT  600
 
 GLuint vs, fs;
 
-void init(int width, int height)
+char * loadFile(const char *fname)
+{
+    struct stat st;
+    if (stat(fname, &st) != 0)
+        return NULL;
+    if (st.st_size <= 0)
+        return NULL;
+    char * buff = new char[st.st_size + 1];
+    buff[st.st_size] = '\0';
+    return buff;
+}
+
+char *getShaderLog(GLuint id)
+{
+    GLint log_length;
+    glGetShaderiv(id, GL_INFO_LOG_LENGTH, &log_length);
+    if (log_length > 0)
+    {
+        char *log = new char[log_length];
+        glGetShaderInfoLog(id, log_length, &log_length, log);
+        return log;
+    }
+    return NULL;
+}
+
+GLuint makeShader(GLenum shaderType, const char *fname)
+{
+    GLuint id;
+    const char *source;
+    GLint status;
+
+    id = glCreateShader(shaderType);
+    if (id <= 0)
+    {
+        cerr << "Error creating shader object" << endl;
+        goto out;
+    }
+
+    source = loadFile(fname);
+    if (source == NULL)
+    {
+        fprintf(stderr, "Error reading file '%s'\n", fname);
+        goto cleanup_shader;
+    }
+
+    glShaderSource(id, 1, &source, NULL);
+    delete[] source;
+
+    glCompileShader(id);
+
+    glGetShaderiv(id, GL_COMPILE_STATUS, &status);
+    if (status != GL_TRUE)
+    {
+        cerr << "Error compiling shader" << endl;
+        char *log = getShaderLog(id);
+        cerr << "Shader Log:" << endl << log << endl;
+        delete[] log;
+        goto cleanup_shader;
+    }
+
+    return id;
+
+cleanup_shader:
+    glDeleteShader(id);
+out:
+    return 0;
+}
+
+bool init(int width, int height)
 {
     glClearColor (0.0, 0.0, 0.0, 0.0);
     glEnable(GL_DEPTH_TEST);
@@ -19,6 +92,16 @@ void init(int width, int height)
             -1, 1, -1, 1);
     glMatrixMode(GL_MODELVIEW);
     glLoadIdentity();
+
+    vs = makeShader(GL_VERTEX_SHADER, "v_shader.glsl");
+    fs = makeShader(GL_FRAGMENT_SHADER, "f_shader.glsl");
+
+    if (vs <= 0 || fs <= 0)
+    {
+        return false;
+    }
+
+    return true;
 }
 
 void display(void)
@@ -47,7 +130,9 @@ int main(int argc, char *argv[])
     }
     SDL_WM_SetCaption(argv[0], argv[0]);
 
-    init(WIDTH, HEIGHT);
+    if (!init(WIDTH, HEIGHT))
+        return 2;
+
     display();
     SDL_Event event;
     while (SDL_WaitEvent(&event))

template/v_shader.glsl

@@ -0,0 +1,4 @@
+
+void main(void)
+{
+}