gl_engine: Introduce tint effect for opengl renderer

issue: https://github.com/thorvg/thorvg/issues/3054

src/renderer/gl_engine/tvgGlCommon.h

@@ -210,6 +210,7 @@ struct GlGaussianBlur {
 
 struct GlEffectParams {
     // fill:          [0..3]: color
+    // tint:          [0..2]: black,  [4..6]: white,   [8]: intensity
     float params[4+4+4];
 };
 

src/renderer/gl_engine/tvgGlRenderTask.cpp

@@ -447,7 +447,7 @@ void GlEffectColorTransformTask::run()
 
     GL_CHECK(glViewport(0, 0, width, height));
     GL_CHECK(glScissor(0, 0, width, height));
-    // we need to make full copy of dst to intermediate buffers to be sure, that they are not contained prev data
+    // we need to make full copy of dst to intermidiate buffers to be shure, that they are not containe prev data
     GL_CHECK(glBindFramebuffer(GL_READ_FRAMEBUFFER, mDstFbo->getFboId()));
     GL_CHECK(glBindFramebuffer(GL_DRAW_FRAMEBUFFER, mDstCopyFbo->getResolveFboId()));
     GL_CHECK(glBlitFramebuffer(0, 0, width, height, 0, 0, width, height, GL_COLOR_BUFFER_BIT, GL_NEAREST));

src/renderer/gl_engine/tvgGlRenderer.cpp

@@ -145,6 +145,7 @@ void GlRenderer::initShaders()
     mPrograms.push(new GlProgram(EFFECT_VERTEX, GAUSSIAN_VERTICAL));
     mPrograms.push(new GlProgram(EFFECT_VERTEX, GAUSSIAN_HORIZONTAL));
     mPrograms.push(new GlProgram(EFFECT_VERTEX, EFFECT_FILL));
+    mPrograms.push(new GlProgram(EFFECT_VERTEX, EFFECT_TINT));
 }
 
 
@@ -975,6 +976,24 @@ void GlRenderer::effectFillUpdate(RenderEffectFill* effect, const Matrix& transf
 }
 
 
+void GlRenderer::effectTintUpdate(RenderEffectTint* effect, const Matrix& transform)
+{
+    auto params = (GlEffectParams*)effect->rd;
+    if (!params) params = tvg::malloc<GlEffectParams*>(sizeof(GlEffectParams));
+    params->params[0] = effect->black[0] / 255.0f;
+    params->params[1] = effect->black[1] / 255.0f;
+    params->params[2] = effect->black[2] / 255.0f;
+    params->params[3] = 0.0f;
+    params->params[4] = effect->white[0] / 255.0f;
+    params->params[5] = effect->white[1] / 255.0f;
+    params->params[6] = effect->white[2] / 255.0f;
+    params->params[7] = 0.0f;
+    params->params[8] = effect->intensity / 255.0f;
+    effect->rd = params;
+    effect->valid = true;
+}
+
+
 bool GlRenderer::effectGaussianBlurRegion(RenderEffectGaussianBlur* effect)
 {
     auto gaussianBlur = (GlGaussianBlur*)effect->rd;
@@ -999,6 +1018,7 @@ void GlRenderer::prepare(RenderEffect* effect, const Matrix& transform)
     switch (effect->type) {
         case SceneEffect::GaussianBlur: effectGaussianBlurUpdate(static_cast<RenderEffectGaussianBlur*>(effect), transform); break;
         case SceneEffect::Fill: effectFillUpdate(static_cast<RenderEffectFill*>(effect), transform); break;
+        case SceneEffect::Tint: effectTintUpdate(static_cast<RenderEffectTint*>(effect), transform); break;
         default: break;
     }
     effect->valid = true;
@@ -1010,6 +1030,7 @@ bool GlRenderer::region(RenderEffect* effect)
     switch (effect->type) {
         case SceneEffect::GaussianBlur: return effectGaussianBlurRegion(static_cast<RenderEffectGaussianBlur*>(effect));
         case SceneEffect::Fill: return true;
+        case SceneEffect::Tint: return true;
         default: return false;
     }
     return false;
@@ -1058,9 +1079,10 @@ bool GlRenderer::render(TVG_UNUSED RenderCompositor* cmp, const RenderEffect* ef
         // add task to render pipeline
         pass->addRenderTask(gaussianTask);
     } // effect fill 
-    else if (effect->type == SceneEffect::Fill) {
+    else if ((effect->type == SceneEffect::Fill) || (effect->type == SceneEffect::Tint)) {
         GlProgram* program{};
         if (effect->type == SceneEffect::Fill) program = mPrograms[RT_EffectFill];
+        else if (effect->type == SceneEffect::Tint) program = mPrograms[RT_EffectTint];
         // get current and intermidiate framebuffers
         auto dstFbo = pass->getFbo();
         auto dstCopyFbo = mBlendPool[0]->getRenderTarget(vp);

src/renderer/gl_engine/tvgGlRenderer.h

@@ -125,6 +125,7 @@ private:
 
     void effectGaussianBlurUpdate(RenderEffectGaussianBlur* effect, const Matrix& transform);
     void effectFillUpdate(RenderEffectFill* effect, const Matrix& transform);
+    void effectTintUpdate(RenderEffectTint* effect, const Matrix& transform);
 
     bool effectGaussianBlurRegion(RenderEffectGaussianBlur* effect);
 

src/renderer/gl_engine/tvgGlShaderSrc.cpp

@@ -776,7 +776,7 @@ void main()
     
     for (int y = -radius; y <= radius; ++y) {
         float weight = gaussian(float(y), sigma);
-        vec2 offset = vec2(0.0, float(y) * texelSize.y);
+        vec2 offset = min(vec2(1.0), vec2(0.0, float(y) * texelSize.y));
         colorSum += texture(uSrcTexture, vUV + offset) * weight;
         weightSum += weight;
     }
@@ -812,7 +812,8 @@ void main()
     
     for (int y = -radius; y <= radius; ++y) {
         float weight = gaussian(float(y), sigma);
-        vec2 offset = vec2(float(y) * texelSize.x, 0.0);
+        //vec2 offset = vec2(float(y) * texelSize.x, 0.0);
+        vec2 offset = min(vec2(1.0), vec2(float(y) * texelSize.x, 0.0));
         colorSum += texture(uSrcTexture, vUV + offset) * weight;
         weightSum += weight;
     }
@@ -837,3 +838,23 @@ void main()
     FragColor = fill * orig.a * fill.a;
 } 
 )";
+
+const char* EFFECT_TINT = R"(
+uniform sampler2D uSrcTexture;
+layout(std140) uniform Params {
+    vec4 params[3];
+} uParams;
+
+in vec2 vUV;
+out vec4 FragColor;
+
+void main()
+{
+    vec4 orig = texture(uSrcTexture, vUV);
+    float luma = dot(orig.rgb, vec3(0.2125, 0.7154, 0.0721));
+    vec4 black = uParams.params[0];
+    vec4 white = uParams.params[1];
+    float intens = uParams.params[2].r;
+    FragColor = mix(orig, mix(white, black, luma), intens) * orig.a;
+} 
+)";

src/renderer/gl_engine/tvgGlShaderSrc.h

@@ -58,5 +58,6 @@ extern const char* EFFECT_VERTEX;
 extern const char* GAUSSIAN_VERTICAL;
 extern const char* GAUSSIAN_HORIZONTAL;
 extern const char* EFFECT_FILL;
+extern const char* EFFECT_TINT;
 
 #endif /* _TVG_GL_SHADERSRC_H_ */