#include <stdio.h>
#include <stdlib.h>
+#include <string>
+#include <sstream>
#include "glutil.h"
-#if defined(CON_GL1)
-#error "GL1 contexts do not support GL2 functionality"
+// extension functions we use
+typedef GLuint (*GLCREATESHADERPROC) (GLenum type);
+typedef void (*GLGETSHADERIVPROC) (GLuint shader, GLenum pname, GLint *params);
+typedef void (*GLGETSHADERINFOLOGPROC) (GLuint shader, GLsizei bufSize, GLsizei *length, GLchar *infoLog);
+typedef void (*GLSHADERSOURCEPROC) (GLuint shader, GLsizei count, const GLchar* const *string, const GLint *length);
+typedef void (*GLCOMPILESHADERPROC) (GLuint shader);
+typedef GLuint (*GLCREATEPROGRAMPROC) (void);
+typedef void (*GLATTACHSHADERPROC) (GLuint program, GLuint shader);
+typedef void (*GLLINKPROGRAMPROC) (GLuint program);
+typedef GLint (*GLGETATTRIBLOCATIONPROC) (GLuint program, const GLchar *name);
+typedef void (*GLUSEPROGRAMPROC) (GLuint program);
+typedef void (*GLVERTEXATTRIBPOINTERPROC) (GLuint index, GLint size, GLenum type, GLboolean normalized, GLsizei stride, const GLvoid *pointer);
+typedef void (*GLENABLEVERTEXATTRIBARRAYPROC) (GLuint index);
+typedef void (*GLGENBUFFERSPROC) (GLsizei n, GLuint *buffers);
+typedef void (*GLBINDBUFFERPROC) (GLenum target, GLuint buffer);
+typedef void (*GLBUFFERDATAPROC) (GLenum target, GLsizeiptr size, const GLvoid *data, GLenum usage);
+typedef void (*GLDELETEBUFFERSPROC) (GLsizei n, const GLuint *buffers);
+
+GLGETSHADERIVPROC p_glGetShaderiv = NULL;
+GLGETSHADERINFOLOGPROC p_glGetShaderInfoLog = NULL;
+GLCREATESHADERPROC p_glCreateShader = NULL;
+GLSHADERSOURCEPROC p_glShaderSource = NULL;
+GLCOMPILESHADERPROC p_glCompileShader = NULL;
+GLCREATEPROGRAMPROC p_glCreateProgram = NULL;
+GLATTACHSHADERPROC p_glAttachShader = NULL;
+GLLINKPROGRAMPROC p_glLinkProgram = NULL;
+GLGETATTRIBLOCATIONPROC p_glGetAttribLocation = NULL;
+GLUSEPROGRAMPROC p_glUseProgram = NULL;
+GLVERTEXATTRIBPOINTERPROC p_glVertexAttribPointer = NULL;
+GLENABLEVERTEXATTRIBARRAYPROC p_glEnableVertexAttribArray = NULL;
+GLGENBUFFERSPROC p_glGenBuffers = NULL;
+GLBINDBUFFERPROC p_glBindBuffer = NULL;
+GLBUFFERDATAPROC p_glBufferData = NULL;
+GLDELETEBUFFERSPROC p_glDeleteBuffers = NULL;
+
+// resolve function pointers
+static T_proc resolveFunctionPointer(T_glGetProcAddress p_glGetProcAddress, const char *name)
+{
+ T_proc proc = p_glGetProcAddress(name);
+ if (proc == NULL) {
+ fprintf(stderr, "Error resolvung function %s\n", name);
+ exit(1);
+ }
+ return proc;
+}
+
+void resolveFunctionPointers(T_glGetProcAddress p_glGetProcAddress)
+{
+#ifdef CON_GL1
+ // we need to check if we have GL 2.0 or greater
+ std::string version = (char*)glGetString(GL_VERSION);
+ std::stringstream ssv(version);
+ std::string major;
+ std::getline(ssv, major, '.');
+ std::stringstream ssm(major);
+ int majorVersion;
+ ssm >> majorVersion;
+ if (majorVersion < 2) {
+ fprintf(stderr, "Need at least GL 2.0 to function properly, but detected version %d\n", majorVersion);
+ exit(1);
+ }
#endif
+
+ // now get the function pointers
+ p_glGetShaderiv = (GLGETSHADERIVPROC)resolveFunctionPointer(p_glGetProcAddress, "glGetShaderiv");
+ p_glGetShaderInfoLog = (GLGETSHADERINFOLOGPROC)resolveFunctionPointer(p_glGetProcAddress, "glGetShaderInfoLog");
+ p_glCreateShader = (GLCREATESHADERPROC)resolveFunctionPointer(p_glGetProcAddress, "glCreateShader");
+ p_glShaderSource = (GLSHADERSOURCEPROC)resolveFunctionPointer(p_glGetProcAddress, "glShaderSource");
+ p_glCompileShader = (GLCOMPILESHADERPROC)resolveFunctionPointer(p_glGetProcAddress, "glCompileShader");
+ p_glCreateProgram = (GLCREATEPROGRAMPROC)resolveFunctionPointer(p_glGetProcAddress, "glCreateProgram");
+ p_glAttachShader = (GLATTACHSHADERPROC)resolveFunctionPointer(p_glGetProcAddress, "glAttachShader");
+ p_glLinkProgram = (GLLINKPROGRAMPROC)resolveFunctionPointer(p_glGetProcAddress, "glLinkProgram");
+ p_glGetAttribLocation = (GLGETATTRIBLOCATIONPROC)resolveFunctionPointer(p_glGetProcAddress, "glGetAttribLocation");
+ p_glUseProgram = (GLUSEPROGRAMPROC)resolveFunctionPointer(p_glGetProcAddress, "glUseProgram");
+ p_glVertexAttribPointer = (GLVERTEXATTRIBPOINTERPROC)resolveFunctionPointer(p_glGetProcAddress, "glVertexAttribPointer");
+ p_glEnableVertexAttribArray = (GLENABLEVERTEXATTRIBARRAYPROC)resolveFunctionPointer(p_glGetProcAddress, "glEnableVertexAttribArray");
+ p_glGenBuffers = (GLGENBUFFERSPROC)resolveFunctionPointer(p_glGetProcAddress, "glGenBuffers");
+ p_glBindBuffer = (GLBINDBUFFERPROC)resolveFunctionPointer(p_glGetProcAddress, "glBindBuffer");
+ p_glBufferData = (GLBUFFERDATAPROC)resolveFunctionPointer(p_glGetProcAddress, "glBufferData");
+ p_glDeleteBuffers = (GLDELETEBUFFERSPROC)resolveFunctionPointer(p_glGetProcAddress, "glDeleteBuffers");
+}
// shaders
static const char *vertex_shader_source =
static void show_info_log(GLuint object)
{
GLint log_length;
- glGetShaderiv(object, GL_INFO_LOG_LENGTH, &log_length);
+ p_glGetShaderiv(object, GL_INFO_LOG_LENGTH, &log_length);
char *log = new char[log_length];
- glGetShaderInfoLog(object, log_length, NULL, log);
+ p_glGetShaderInfoLog(object, log_length, NULL, log);
fprintf(stderr, "%s", log);
delete[] log;
}
static GLuint compile_shader(GLenum shader_type, const char *source)
{
- GLuint shader = glCreateShader(shader_type);
- glShaderSource(shader, 1, &source, NULL);
- glCompileShader(shader);
+ GLuint shader = p_glCreateShader(shader_type);
+ p_glShaderSource(shader, 1, &source, NULL);
+ p_glCompileShader(shader);
GLint shader_ok;
- glGetShaderiv(shader, GL_COMPILE_STATUS, &shader_ok);
+ p_glGetShaderiv(shader, GL_COMPILE_STATUS, &shader_ok);
if (!shader_ok) {
fprintf(stderr, "Failed to compile shader\n");
show_info_log(shader);
static GLuint createArrayBuffer(GLsizeiptr size, GLfloat *data)
{
GLuint buffer;
- glGenBuffers(1, &buffer);
- glBindBuffer(GL_ARRAY_BUFFER, buffer);
- glBufferData(GL_ARRAY_BUFFER, size, data, GL_STATIC_DRAW);
+ p_glGenBuffers(1, &buffer);
+ p_glBindBuffer(GL_ARRAY_BUFFER, buffer);
+ p_glBufferData(GL_ARRAY_BUFFER, size, data, GL_STATIC_DRAW);
return buffer;
}
{
GLuint vertex_shader = compile_shader(GL_VERTEX_SHADER, vertex_shader_source);
GLuint fragment_shader = compile_shader(GL_FRAGMENT_SHADER, fragment_shader_source);
- program = glCreateProgram();
- glAttachShader(program, vertex_shader);
- glAttachShader(program, fragment_shader);
- glLinkProgram(program);
- attributes.position = glGetAttribLocation(program, "position");
- attributes.color = glGetAttribLocation(program, "color");
+ program = p_glCreateProgram();
+ p_glAttachShader(program, vertex_shader);
+ p_glAttachShader(program, fragment_shader);
+ p_glLinkProgram(program);
+ attributes.position = p_glGetAttribLocation(program, "position");
+ attributes.color = p_glGetAttribLocation(program, "color");
}
// draw a quad
void drawQuad(GLfloat red, GLfloat green, GLfloat blue, GLfloat x1, GLfloat y1, GLfloat x2, GLfloat y2)
{
- glUseProgram(program);
+ p_glUseProgram(program);
// send vertex data to card with given attribute
GLfloat vertex_buffer_data[] = {
x1, y2,
};
GLuint vertex_buffer = createArrayBuffer(sizeof(vertex_buffer_data), vertex_buffer_data);
- glVertexAttribPointer(
+ p_glVertexAttribPointer(
attributes.position, /* attribute */
2, /* size */
GL_FLOAT, /* type */
0, /* stride */
(void*)0 /* array buffer offset */
);
- glEnableVertexAttribArray(attributes.position);
+ p_glEnableVertexAttribArray(attributes.position);
// same with color data
GLfloat color_buffer_data[] = {
red, green, blue,
};
GLuint color_buffer = createArrayBuffer(sizeof(color_buffer_data), color_buffer_data);
- glVertexAttribPointer(
+ p_glVertexAttribPointer(
attributes.color, /* attribute */
3, /* size */
GL_FLOAT, /* type */
0, /* stride */
(void*)0 /* array buffer offset */
);
- glEnableVertexAttribArray(attributes.color);
+ p_glEnableVertexAttribArray(attributes.color);
// draw
glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
// cleanup
- glDeleteBuffers(1, &vertex_buffer);
- glDeleteBuffers(1, &color_buffer);
+ p_glDeleteBuffers(1, &vertex_buffer);
+ p_glDeleteBuffers(1, &color_buffer);
}
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