Add texture loading (and render in test)

1 files changed, 71 insertions, 0 deletions

diff --git a/src/graphics/texture.c b/src/graphics/texture.c
new file mode 100644
index 0000000..3d3ea6f
--- /dev/null
+++ b/src/graphics/texture.c
@@ -0,0 +1,71 @@
+#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_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 */
+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_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;
+    }
+}