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65 lines
2.3 KiB
C++
65 lines
2.3 KiB
C++
#include "load_textures.h"
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#define STB_IMAGE_IMPLEMENTATION
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#include "stb_image.h"
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#define STB_IMAGE_RESIZE_IMPLEMENTATION
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#include "stb_image_resize.h"
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bool GL_LoadTextureFromFile(const char* filename, GLuint* out_texture, int* out_width, int* out_height, int maxwidth)
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{
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// load the image
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int image_width = 0;
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int image_height = 0;
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int channels;
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auto image_data = stbi_load(filename, &image_width, &image_height, &channels, STBI_rgb_alpha);
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if (!image_data)
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return false;
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// reduce the image
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float ratio = 1;
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if (image_width > maxwidth && maxwidth != 0) {
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ratio = maxwidth / static_cast<float>(image_width);
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}
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int image_width_resized = image_width * ratio;
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int image_height_resized = image_height * ratio;
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if (ratio != 1)
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{
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unsigned char* image_data_resized = (unsigned char*)stbi__malloc(image_width_resized * image_height_resized * 4);
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if (!image_data_resized) {
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stbi_image_free(image_data);
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return false;
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}
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stbir_resize_uint8(image_data, image_width, image_height, 0,
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image_data_resized, image_width_resized, image_height_resized, 0,
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4);
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stbi_image_free(image_data);
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image_data = image_data_resized;
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}
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// Create a OpenGL texture identifier
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GLuint image_texture;
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glGenTextures(1, &image_texture);
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glBindTexture(GL_TEXTURE_2D, image_texture);
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// Setup filtering parameters for display
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); // This is required on WebGL for non power-of-two textures
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); // Same
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// Upload pixels into texture
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#if defined(GL_UNPACK_ROW_LENGTH) && !defined(__EMSCRIPTEN__)
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glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
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#endif
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glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, image_width_resized, image_height_resized, 0, GL_RGBA, GL_UNSIGNED_BYTE, image_data);
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stbi_image_free(image_data);
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*out_texture = image_texture;
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*out_width = image_width_resized;
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*out_height = image_height_resized;
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return true;
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}
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