[libcamera-devel] [PATCH v5 1/9] qcam: viewfinder_gl: change uniform float tex_stepx to vec2 tex_step

[Andrey Konovalov]

In preparation to extend the supported formats, extend the tex_stepx
uniform to cover the steps between texels in both horizontal and
vertical directions.

Signed-off-by: Andrey Konovalov <andrey.konovalov at linaro.org>
---
 src/qcam/assets/shader/YUV_packed.frag | 8 ++++----
 src/qcam/viewfinder_gl.cpp             | 7 ++++---
 src/qcam/viewfinder_gl.h               | 2 +-
 3 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/src/qcam/assets/shader/YUV_packed.frag b/src/qcam/assets/shader/YUV_packed.frag
index 224dfafe..d6efd4ce 100644
--- a/src/qcam/assets/shader/YUV_packed.frag
+++ b/src/qcam/assets/shader/YUV_packed.frag
@@ -12,7 +12,7 @@ precision mediump float;
 varying vec2 textureOut;
 
 uniform sampler2D tex_y;
-uniform float tex_stepx;
+uniform vec2 tex_step;
 
 void main(void)
 {
@@ -49,10 +49,10 @@ void main(void)
 	 * a = fract(x) * 2 - 1			if fract(x) >= 0.5
 	 */
 	vec2 pos = textureOut;
-	float f_x = fract(pos.x / tex_stepx);
+	float f_x = fract(pos.x / tex_step.x);
 
-	vec4 left = texture2D(tex_y, vec2(pos.x - f_x * tex_stepx, pos.y));
-	vec4 right = texture2D(tex_y, vec2(pos.x + (1.0 - f_x) * tex_stepx , pos.y));
+	vec4 left = texture2D(tex_y, vec2(pos.x - f_x * tex_step.x, pos.y));
+	vec4 right = texture2D(tex_y, vec2(pos.x + (1.0 - f_x) * tex_step.x , pos.y));
 
 #if defined(YUV_PATTERN_UYVY)
 	float y_left = mix(left.g, left.a, f_x * 2.0);
diff --git a/src/qcam/viewfinder_gl.cpp b/src/qcam/viewfinder_gl.cpp
index 5d9b442e..ff719418 100644
--- a/src/qcam/viewfinder_gl.cpp
+++ b/src/qcam/viewfinder_gl.cpp
@@ -289,7 +289,7 @@ bool ViewFinderGL::createFragmentShader()
 	textureUniformY_ = shaderProgram_.uniformLocation("tex_y");
 	textureUniformU_ = shaderProgram_.uniformLocation("tex_u");
 	textureUniformV_ = shaderProgram_.uniformLocation("tex_v");
-	textureUniformStepX_ = shaderProgram_.uniformLocation("tex_stepx");
+	textureUniformStep_ = shaderProgram_.uniformLocation("tex_step");
 
 	/* Create the textures. */
 	for (std::unique_ptr<QOpenGLTexture> &texture : textures_) {
@@ -508,8 +508,9 @@ void ViewFinderGL::doRender()
 		 * ([0, 1]). There are exactly width - 1 steps between the
 		 * leftmost and rightmost texels.
 		 */
-		shaderProgram_.setUniformValue(textureUniformStepX_,
-					       1.0f / (size_.width() / 2 - 1));
+		shaderProgram_.setUniformValue(textureUniformStep_,
+					       1.0f / (size_.width() / 2 - 1),
+					       1.0f /* not used */);
 		break;
 
 	case libcamera::formats::ABGR8888:
diff --git a/src/qcam/viewfinder_gl.h b/src/qcam/viewfinder_gl.h
index 150fa4ae..1b1faa91 100644
--- a/src/qcam/viewfinder_gl.h
+++ b/src/qcam/viewfinder_gl.h
@@ -85,7 +85,7 @@ private:
 	GLuint textureUniformU_;
 	GLuint textureUniformV_;
 	GLuint textureUniformY_;
-	GLuint textureUniformStepX_;
+	GLuint textureUniformStep_;
 	unsigned int horzSubSample_;
 	unsigned int vertSubSample_;
 
-- 
2.25.1