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Added the concept of colorspace to the SDL renderer

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This allows color operations to happen in linear space between sRGB input and sRGB output. This is currently supported on the direct3d11, direct3d12 and opengl renderers.

This is a good resource on blending in linear space vs sRGB space:
https://blog.johnnovak.net/2016/09/21/what-every-coder-should-know-about-gamma/

Also added testcolorspace to verify colorspace changes
This commit is contained in:
Sam Lantinga 2024-01-29 18:32:27 -08:00
parent 554f0625d3
commit f257eb4481
9 changed files with 648 additions and 40 deletions
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28
src/render/opengl/SDL_render_gl.c
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@ -49,8 +49,6 @@
http://developer.apple.com/library/mac/#documentation/GraphicsImaging/Conceptual/OpenGL-MacProgGuide/opengl_texturedata/opengl_texturedata.html
*/
static const float inv255f = 1.0f / 255.0f;
typedef struct GL_FBOList GL_FBOList;
struct GL_FBOList
@ -403,19 +401,27 @@ static SDL_bool GL_SupportsBlendMode(SDL_Renderer *renderer, SDL_BlendMode blend
return SDL_TRUE;
}
static SDL_bool convert_format(GL_RenderData *renderdata, Uint32 pixel_format,
static SDL_bool convert_format(Uint32 pixel_format, Uint32 colorspace, SDL_bool colorspace_conversion,
GLint *internalFormat, GLenum *format, GLenum *type)
{
switch (pixel_format) {
case SDL_PIXELFORMAT_ARGB8888:
case SDL_PIXELFORMAT_XRGB8888:
*internalFormat = GL_RGBA8;
if (colorspace_conversion && colorspace == SDL_COLORSPACE_SRGB) {
*internalFormat = GL_SRGB8_ALPHA8;
} else {
*internalFormat = GL_RGBA8;
}
*format = GL_BGRA;
*type = GL_UNSIGNED_INT_8_8_8_8_REV;
break;
case SDL_PIXELFORMAT_ABGR8888:
case SDL_PIXELFORMAT_XBGR8888:
*internalFormat = GL_RGBA8;
if (colorspace_conversion && colorspace == SDL_COLORSPACE_SRGB) {
*internalFormat = GL_SRGB8_ALPHA8;
} else {
*internalFormat = GL_RGBA8;
}
*format = GL_RGBA;
*type = GL_UNSIGNED_INT_8_8_8_8_REV;
break;
@ -460,8 +466,8 @@ static int GL_CreateTexture(SDL_Renderer *renderer, SDL_Texture *texture, SDL_Pr
return SDL_SetError("Render targets not supported by OpenGL");
}
if (!convert_format(renderdata, texture->format, &internalFormat,
&format, &type)) {
if (!convert_format(texture->format, texture->colorspace, renderer->colorspace_conversion,
&internalFormat, &format, &type)) {
return SDL_SetError("Texture format %s not supported by OpenGL",
SDL_GetPixelFormatName(texture->format));
}
@ -1475,7 +1481,8 @@ static int GL_RenderReadPixels(SDL_Renderer *renderer, const SDL_Rect *rect,
GL_ActivateRenderer(renderer);
if (!convert_format(data, temp_format, &internalFormat, &format, &type)) {
if (!convert_format(temp_format, renderer->input_colorspace, renderer->colorspace_conversion,
&internalFormat, &format, &type)) {
return SDL_SetError("Texture format %s not supported by OpenGL",
SDL_GetPixelFormatName(temp_format));
}
@ -1709,6 +1716,8 @@ static SDL_Renderer *GL_CreateRenderer(SDL_Window *window, SDL_PropertiesID crea
goto error;
}
SDL_SetupRendererColorspace(renderer, create_props);
renderer->WindowEvent = GL_WindowEvent;
renderer->SupportsBlendMode = GL_SupportsBlendMode;
renderer->CreateTexture = GL_CreateTexture;
@ -1910,6 +1919,9 @@ static SDL_Renderer *GL_CreateRenderer(SDL_Window *window, SDL_PropertiesID crea
data->glDisable(data->textype);
data->glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
data->glColor4f(1.0f, 1.0f, 1.0f, 1.0f);
if (renderer->colorspace_conversion && renderer->output_colorspace == SDL_COLORSPACE_SRGB) {
data->glEnable(GL_FRAMEBUFFER_SRGB);
}
/* This ended up causing video discrepancies between OpenGL and Direct3D */
/* data->glEnable(GL_LINE_SMOOTH); */