bradgrantham-apple2e/gl_utility.cpp

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#include <cstdlib>
#include <cstdio>
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#define GL_SILENCE_DEPRECATION
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#if defined(__linux__)
#include <GL/glew.h>
#endif // defined(__linux__)
#define GLFW_INCLUDE_GLCOREARB
#include <GLFW/glfw3.h>
#include "gl_utility.h"
void CheckOpenGL(const char *filename, int line)
{
int glerr;
static bool stored_exit_flag = false;
static bool exit_on_error;
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if(!stored_exit_flag) {
exit_on_error = getenv("EXIT_ON_OPENGL_ERROR") != NULL;
stored_exit_flag = true;
}
while((glerr = glGetError()) != GL_NO_ERROR) {
printf("GL Error: %04X at %s:%d\n", glerr, filename, line);
if(exit_on_error)
exit(1);
}
}
// Destroy render target resources
render_target::~render_target()
{
glDeleteTextures(1, &color);
glDeleteRenderbuffers(1, &depth);
glDeleteFramebuffers(1, &framebuffer);
}
// Create render target resources if possible
render_target::render_target(int w, int h)
{
GLenum status;
// Create color texture
glGenTextures(1, &color);
glBindTexture(GL_TEXTURE_2D, color);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
CheckOpenGL(__FILE__, __LINE__);
// Create depth texture
glGenTextures(1, &depth);
glBindTexture(GL_TEXTURE_2D, depth);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT16, w, h, 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_INT, NULL);
CheckOpenGL(__FILE__, __LINE__);
glGenFramebuffers(1, &framebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
CheckOpenGL(__FILE__, __LINE__);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, color, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, depth, 0);
CheckOpenGL(__FILE__, __LINE__);
status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
if(status != GL_FRAMEBUFFER_COMPLETE) {
fprintf(stderr, "framebuffer status was %04X\n", status);
throw "Couldn't create OpenGL framebuffer";
}
CheckOpenGL(__FILE__, __LINE__);
glBindFramebuffer(GL_FRAMEBUFFER, 0);
}
bool gPrintShaderLog = true;
bool CheckShaderCompile(GLuint shader, const std::string& shader_name)
{
int status;
glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
if(status == GL_TRUE)
return true;
if(gPrintShaderLog) {
int length;
glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &length);
if (length > 0) {
char log[length];
glGetShaderInfoLog(shader, length, NULL, log);
fprintf(stderr, "%s shader error log:\n%s\n", shader_name.c_str(), log);
}
fprintf(stderr, "%s compile failure.\n", shader_name.c_str());
fprintf(stderr, "shader text:\n");
glGetShaderiv(shader, GL_SHADER_SOURCE_LENGTH, &length);
char source[length];
glGetShaderSource(shader, length, NULL, source);
fprintf(stderr, "%s\n", source);
}
return false;
}
bool CheckProgramLink(GLuint program)
{
int status;
glGetProgramiv(program, GL_LINK_STATUS, &status);
if(status == GL_TRUE)
return true;
if(gPrintShaderLog) {
int log_length;
glGetProgramiv(program, GL_INFO_LOG_LENGTH, &log_length);
if (log_length > 0) {
char log[log_length];
glGetProgramInfoLog(program, log_length, NULL, log);
fprintf(stderr, "program error log: %s\n",log);
}
}
return false;
}
void opengl_texture::load(int w_, int h_, const unsigned char *pixels)
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{
w = w_;
h = h_;
glBindTexture(GL_TEXTURE_2D, t);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, w, h, 0, GL_RED, GL_UNSIGNED_BYTE, pixels);
glBindTexture(GL_TEXTURE_2D, GL_NONE);
}
opengl_texture initialize_texture(int w, int h, const unsigned char *pixels)
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{
GLuint tex;
glGenTextures(1, &tex);
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opengl_texture t = {w, h, tex};
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glBindTexture(GL_TEXTURE_2D, tex);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
CheckOpenGL(__FILE__, __LINE__);
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t.load(w, h, pixels);
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CheckOpenGL(__FILE__, __LINE__);
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return t;
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}
GLuint GenerateProgram(const std::string& shader_name, const std::string& vertex_shader_text, const std::string& fragment_shader_text)
{
std::string spec_string;
spec_string = "#version 140\n";
// reset line number so that I can view errors with the line number
// they have in the base shaders.
spec_string += "#line 0\n";
std::string vertex_shader_string = spec_string + vertex_shader_text;
std::string fragment_shader_string = spec_string + fragment_shader_text;
GLuint vertex_shader = glCreateShader(GL_VERTEX_SHADER);
const char *string = vertex_shader_string.c_str();
glShaderSource(vertex_shader, 1, &string, NULL);
glCompileShader(vertex_shader);
if(!CheckShaderCompile(vertex_shader, shader_name + " vertex shader"))
return 0;
GLuint fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
string = fragment_shader_string.c_str();
glShaderSource(fragment_shader, 1, &string, NULL);
glCompileShader(fragment_shader);
if(!CheckShaderCompile(fragment_shader, shader_name + " fragment shader"))
return 0;
CheckOpenGL(__FILE__, __LINE__);
GLuint program = glCreateProgram();
glAttachShader(program, vertex_shader);
glAttachShader(program, fragment_shader);
CheckOpenGL(__FILE__, __LINE__);
glLinkProgram(program);
CheckOpenGL(__FILE__, __LINE__);
if(!CheckProgramLink(program))
return 0;
return program;
}
GLuint make_rectangle_array_buffer(float x, float y, float w, float h)
{
/* just x, y, also pixel coords */
GLuint vertices;
glGenBuffers(1, &vertices);
glBindBuffer(GL_ARRAY_BUFFER, vertices);
float coords[4][2] = {
{x, y},
{x + w, y},
{x, y + h},
{x + w, y + h},
};
glBufferData(GL_ARRAY_BUFFER, sizeof(coords[0]) * 4, coords, GL_STATIC_DRAW);
CheckOpenGL(__FILE__, __LINE__);
return vertices;
}