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#include "../../include/mgl/graphics/texture.h"
#include "../../include/mgl/mgl.h"
#define STBI_NO_PSD
#define STBI_NO_TGA
#define STBI_NO_HDR
#define STBI_NO_PIC
#define STBI_NO_PNM
#define STB_IMAGE_IMPLEMENTATION
#include "../../external/stb_image.h"
static int mgl_texture_format_to_opengl_format(mgl_texture_format format) {
switch(format) {
case MGL_TEXTURE_GRAY: return GL_LUMINANCE8;
case MGL_TEXTURE_GRAY_ALPHA: return GL_LUMINANCE8_ALPHA8;
case MGL_TEXTURE_RGB: return GL_RGB8;
case MGL_TEXTURE_RGB_ALPHA: return GL_RGBA8;
}
return 0;
}
static int mgl_texture_format_to_compressed_opengl_format(mgl_texture_format format) {
switch(format) {
case MGL_TEXTURE_GRAY: return GL_LUMINANCE8;
case MGL_TEXTURE_GRAY_ALPHA: return GL_LUMINANCE8_ALPHA8;
case MGL_TEXTURE_RGB: return GL_COMPRESSED_RGB_S3TC_DXT1_EXT;
case MGL_TEXTURE_RGB_ALPHA: return GL_COMPRESSED_RGBA_S3TC_DXT5_EXT;
}
return 0;
}
static int mgl_texture_format_to_source_opengl_format(mgl_texture_format format) {
switch(format) {
case MGL_TEXTURE_GRAY: return GL_LUMINANCE8_ALPHA8;
case MGL_TEXTURE_GRAY_ALPHA: return GL_LUMINANCE8_ALPHA8;
case MGL_TEXTURE_RGB: return GL_RGB;
case MGL_TEXTURE_RGB_ALPHA: return GL_RGBA;
}
return 0;
}
/* TODO: Ensure texture is power of 2 if the hardware doesn't support non power of two textures */
/* TODO: Verify if source format should always be 4 components (RGBA) because apparently if its another format then opengl will internally convert it to RGBA */
int mgl_texture_load_from_file(mgl_texture *self, const char *filepath) {
self->id = 0;
int format;
stbi_uc *image_data = stbi_load(filepath, &self->width, &self->height, &format, 0);
if(!image_data) {
fprintf(stderr, "Error: failed to load image %s, error: %s\n", filepath, stbi_failure_reason());
return -1;
}
self->format = format;
mgl_context *context = mgl_get_context();
context->gl.glGenTextures(1, &self->id);
if(self->id == 0) {
stbi_image_free(image_data);
return -1;
}
const int opengl_texture_format = mgl_texture_format_to_compressed_opengl_format(self->format);
context->gl.glBindTexture(GL_TEXTURE_2D, self->id);
context->gl.glTexImage2D(GL_TEXTURE_2D, 0, opengl_texture_format, self->width, self->height, 0, mgl_texture_format_to_source_opengl_format(self->format), GL_UNSIGNED_BYTE, image_data);
context->gl.glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
context->gl.glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
context->gl.glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
context->gl.glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
context->gl.glBindTexture(GL_TEXTURE_2D, 0);
stbi_image_free(image_data);
return 0;
}
void mgl_texture_unload(mgl_texture *self) {
mgl_context *context = mgl_get_context();
if(self->id) {
context->gl.glDeleteTextures(1, &self->id);
self->id = 0;
}
}
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