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Finalized the SDL render API colorspaces

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The renderer will always use the sRGB colorspace for drawing, and will default to the sRGB output colorspace. If you want blending in linear space and HDR support, you can select the scRGB output colorspace, which is supported by the direct3d11 and direct3d12
This commit is contained in:
Sam Lantinga
2024-02-02 12:09:37 -08:00
parent 7c089f4e57
commit 9591b2cfb4
12 changed files with 195 additions and 248 deletions
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89
test/testcolorspace.c
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@@ -51,9 +51,7 @@ static void CreateRenderer(void)
props = SDL_CreateProperties();
SDL_SetProperty(props, SDL_PROP_RENDERER_CREATE_WINDOW_POINTER, window);
SDL_SetStringProperty(props, SDL_PROP_RENDERER_CREATE_NAME_STRING, SDL_GetRenderDriver(renderer_index));
SDL_SetNumberProperty(props, SDL_PROP_RENDERER_CREATE_INPUT_COLORSPACE_NUMBER, SDL_COLORSPACE_SRGB);
SDL_SetNumberProperty(props, SDL_PROP_RENDERER_CREATE_OUTPUT_COLORSPACE_NUMBER, colorspace);
SDL_SetBooleanProperty(props, SDL_PROP_RENDERER_CREATE_COLORSPACE_CONVERSION_BOOLEAN, SDL_TRUE);
renderer = SDL_CreateRendererWithProperties(props);
SDL_DestroyProperties(props);
if (!renderer) {
@@ -254,13 +252,13 @@ static void RenderBlendDrawing(void)
float y = TEXT_START_Y;
DrawText(x, y, "%s %s", renderer_name, colorspace_name);
y += TEXT_LINE_ADVANCE;
DrawText(x, y, "Test: Draw Linear Blending");
DrawText(x, y, "Test: Draw Blending");
y += TEXT_LINE_ADVANCE;
if (cr.r == 199 && cr.g == 193 && cr.b == 121) {
DrawText(x, y, "Correct blend color in linear space");
DrawText(x, y, "Correct blend color, blending in linear space");
} else if ((cr.r == 192 && cr.g == 163 && cr.b == 83) ||
(cr.r == 191 && cr.g == 162 && cr.b == 82)) {
DrawText(x, y, "Incorrect blend color, blending in sRGB space");
DrawText(x, y, "Correct blend color, blending in sRGB space");
} else if (cr.r == 214 && cr.g == 156 && cr.b == 113) {
DrawText(x, y, "Incorrect blend color, blending in PQ space");
} else {
@@ -314,13 +312,13 @@ static void RenderBlendTexture(void)
float y = TEXT_START_Y;
DrawText(x, y, "%s %s", renderer_name, colorspace_name);
y += TEXT_LINE_ADVANCE;
DrawText(x, y, "Test: Texture Linear Blending");
DrawText(x, y, "Test: Texture Blending");
y += TEXT_LINE_ADVANCE;
if (cr.r == 199 && cr.g == 193 && cr.b == 121) {
DrawText(x, y, "Correct blend color in linear space");
DrawText(x, y, "Correct blend color, blending in linear space");
} else if ((cr.r == 192 && cr.g == 163 && cr.b == 83) ||
(cr.r == 191 && cr.g == 162 && cr.b == 82)) {
DrawText(x, y, "Incorrect blend color, blending in sRGB space");
DrawText(x, y, "Correct blend color, blending in sRGB space");
} else {
DrawText(x, y, "Incorrect blend color, unknown reason");
}
@@ -351,13 +349,10 @@ static void DrawGradient(float x, float y, float width, float height, float star
xy[0] = minx;
xy[1] = miny;
xy[2] = maxx;
xy[3] = miny;
xy[4] = maxx;
xy[5] = maxy;
xy[6] = minx;
xy[7] = maxy;
@@ -369,6 +364,36 @@ static void DrawGradient(float x, float y, float width, float height, float star
SDL_RenderGeometryRaw(renderer, NULL, xy, xy_stride, color, color_stride, NULL, 0, num_vertices, indices, num_indices, size_indices);
}
static float scRGBfromNits(float v)
{
return v / 80.0f;
}
static float sRGBtoLinear(float v)
{
if (v <= 0.04045f) {
v = (v / 12.92f);
} else {
v = SDL_powf(((v + 0.055f) / 1.055f), 2.4f);
}
return v;
}
static float sRGBFromLinear(float v)
{
if (v <= 0.0031308f) {
v = (v * 12.92f);
} else {
v = (SDL_powf(v, 1.0f / 2.4f) * 1.055f - 0.055f);
}
return v;
}
static float sRGBfromNits(float v)
{
return sRGBFromLinear(scRGBfromNits(v));
}
static void RenderGradientDrawing(void)
{
SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
@@ -383,29 +408,25 @@ static void RenderGradientDrawing(void)
y += TEXT_LINE_ADVANCE;
DrawTextWhite(x, y, "SDR mathematically linear gradient (%d nits)", 80);
DrawTextWhite(x, y, "SDR gradient (%d nits)", 80);
y += TEXT_LINE_ADVANCE;
DrawGradient(x, y, WINDOW_WIDTH - 2 * x, 64.0f, 0.0f, 1.0f);
DrawGradient(x, y, WINDOW_WIDTH - 2 * x, 64.0f, 0.0f, sRGBfromNits(80.0f));
y += 64.0f;
y += TEXT_LINE_ADVANCE;
y += TEXT_LINE_ADVANCE;
DrawTextWhite(x, y, "HDR mathematically linear gradient (%d nits)", 400);
DrawTextWhite(x, y, "HDR gradient (%d nits)", 400);
y += TEXT_LINE_ADVANCE;
SDL_SetRenderDrawColorspace(renderer, SDL_COLORSPACE_SCRGB);
DrawGradient(x, y, WINDOW_WIDTH - 2 * x, 64.0f, 0.0f, 5.0f);
SDL_SetRenderDrawColorspace(renderer, SDL_COLORSPACE_SRGB);
DrawGradient(x, y, WINDOW_WIDTH - 2 * x, 64.0f, 0.0f, sRGBfromNits(400.0f));
y += 64.0f;
y += TEXT_LINE_ADVANCE;
y += TEXT_LINE_ADVANCE;
DrawTextWhite(x, y, "HDR mathematically linear gradient (%d nits)", 1000);
DrawTextWhite(x, y, "HDR gradient (%d nits)", 1000);
y += TEXT_LINE_ADVANCE;
SDL_SetRenderDrawColorspace(renderer, SDL_COLORSPACE_SCRGB);
DrawGradient(x, y, WINDOW_WIDTH - 2 * x, 64.0f, 0.0f, 12.5f);
SDL_SetRenderDrawColorspace(renderer, SDL_COLORSPACE_SRGB);
DrawGradient(x, y, WINDOW_WIDTH - 2 * x, 64.0f, 0.0f, sRGBfromNits(1000));
y += 64.0f;
}
@@ -414,19 +435,27 @@ static SDL_Texture *CreateGradientTexture(int width, float start, float end)
SDL_Texture *texture;
float *pixels;
/* Floating point textures are in the scRGB colorspace by default */
texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_RGBA128_FLOAT, SDL_TEXTUREACCESS_STATIC, width, 1);
if (!texture) {
return NULL;
}
if (colorspace == SDL_COLORSPACE_SCRGB) {
/* The input values are in the sRGB colorspace, but we're blending in linear space */
start = sRGBtoLinear(start);
end = sRGBtoLinear(end);
} else if (colorspace == SDL_COLORSPACE_SRGB) {
/* The input values are in the sRGB colorspace, and we're blending in sRGB space */
}
pixels = (float *)SDL_malloc(width * sizeof(float) * 4);
if (pixels) {
int i;
float length = (end - start);
for (i = 0; i < width; ++i) {
/* Use a 2.4 gamma function to create a perceptually linear gradient */
float v = SDL_powf(start + (length * i) / width, 2.4f);
float v = (start + (length * i) / width);
pixels[i * 4 + 0] = v;
pixels[i * 4 + 1] = v;
pixels[i * 4 + 2] = v;
@@ -455,30 +484,30 @@ static void RenderGradientTexture(void)
float y = TEXT_START_Y;
DrawTextWhite(x, y, "%s %s", renderer_name, colorspace_name);
y += TEXT_LINE_ADVANCE;
DrawTextWhite(x, y, "Test: Draw SDR and HDR gradients");
DrawTextWhite(x, y, "Test: Texture SDR and HDR gradients");
y += TEXT_LINE_ADVANCE;
y += TEXT_LINE_ADVANCE;
DrawTextWhite(x, y, "SDR perceptually linear gradient (%d nits)", 80);
DrawTextWhite(x, y, "SDR gradient (%d nits)", 80);
y += TEXT_LINE_ADVANCE;
DrawGradientTexture(x, y, WINDOW_WIDTH - 2 * x, 64.0f, 0.0f, 1.0f);
DrawGradientTexture(x, y, WINDOW_WIDTH - 2 * x, 64.0f, 0.0f, sRGBfromNits(80));
y += 64.0f;
y += TEXT_LINE_ADVANCE;
y += TEXT_LINE_ADVANCE;
DrawTextWhite(x, y, "HDR perceptually linear gradient (%d nits)", 400);
DrawTextWhite(x, y, "HDR gradient (%d nits)", 400);
y += TEXT_LINE_ADVANCE;
DrawGradientTexture(x, y, WINDOW_WIDTH - 2 * x, 64.0f, 0.0f, 5.0f);
DrawGradientTexture(x, y, WINDOW_WIDTH - 2 * x, 64.0f, 0.0f, sRGBfromNits(400));
y += 64.0f;
y += TEXT_LINE_ADVANCE;
y += TEXT_LINE_ADVANCE;
DrawTextWhite(x, y, "HDR perceptually linear gradient (%d nits)", 1000);
DrawTextWhite(x, y, "HDR gradient (%d nits)", 1000);
y += TEXT_LINE_ADVANCE;
DrawGradientTexture(x, y, WINDOW_WIDTH - 2 * x, 64.0f, 0.0f, 12.5f);
DrawGradientTexture(x, y, WINDOW_WIDTH - 2 * x, 64.0f, 0.0f, sRGBfromNits(1000));
y += 64.0f;
}