Draw video if everything bypassed

apps/RenderCadenceCompositor/render/SimpleMotionRenderer.cpp

@@ -3,8 +3,43 @@
 #include "GLExtensions.h"
 
 #include <algorithm>
+#include <array>
 #include <cmath>
 
+namespace
+{
+constexpr GLuint kInputTextureUnit = 0;
+
+const char* kTextureVertexShader = R"GLSL(
+#version 430 core
+out vec2 vTexCoord;
+void main()
+{
+	vec2 positions[3] = vec2[3](
+		vec2(-1.0, -1.0),
+		vec2( 3.0, -1.0),
+		vec2(-1.0,  3.0));
+	vec2 texCoords[3] = vec2[3](
+		vec2(0.0, 0.0),
+		vec2(2.0, 0.0),
+		vec2(0.0, 2.0));
+	gl_Position = vec4(positions[gl_VertexID], 0.0, 1.0);
+	vTexCoord = texCoords[gl_VertexID];
+}
+)GLSL";
+
+const char* kTextureFragmentShader = R"GLSL(
+#version 430 core
+layout(binding = 0) uniform sampler2D uInputTexture;
+in vec2 vTexCoord;
+out vec4 fragColor;
+void main()
+{
+	fragColor = texture(uInputTexture, clamp(vTexCoord, vec2(0.0), vec2(1.0)));
+}
+)GLSL";
+}
+
 bool SimpleMotionRenderer::InitializeGl(unsigned width, unsigned height)
 {
 	mWidth = width;
@@ -43,8 +78,100 @@ void SimpleMotionRenderer::RenderFrame(uint64_t frameIndex)
 	glDisable(GL_SCISSOR_TEST);
 }
 
+void SimpleMotionRenderer::RenderTexture(GLuint texture)
+{
+	if (texture == 0 || !EnsureTextureProgram())
+	{
+		RenderFrame(0);
+		return;
+	}
+
+	glViewport(0, 0, static_cast<GLsizei>(mWidth), static_cast<GLsizei>(mHeight));
+	glDisable(GL_SCISSOR_TEST);
+	glDisable(GL_DEPTH_TEST);
+	glDisable(GL_BLEND);
+	glActiveTexture(GL_TEXTURE0 + kInputTextureUnit);
+	glBindTexture(GL_TEXTURE_2D, texture);
+	glUseProgram(mTextureProgram);
+	glBindVertexArray(mTextureVertexArray);
+	glDrawArrays(GL_TRIANGLES, 0, 3);
+	glBindVertexArray(0);
+	glUseProgram(0);
+	glBindTexture(GL_TEXTURE_2D, 0);
+	glActiveTexture(GL_TEXTURE0);
+}
+
 void SimpleMotionRenderer::ShutdownGl()
 {
+	DestroyTextureProgram();
 	mWidth = 0;
 	mHeight = 0;
 }
+
+bool SimpleMotionRenderer::EnsureTextureProgram()
+{
+	if (mTextureProgram != 0)
+		return true;
+
+	if (!CompileShader(GL_VERTEX_SHADER, kTextureVertexShader, mTextureVertexShader))
+		return false;
+	if (!CompileShader(GL_FRAGMENT_SHADER, kTextureFragmentShader, mTextureFragmentShader))
+	{
+		DestroyTextureProgram();
+		return false;
+	}
+
+	mTextureProgram = glCreateProgram();
+	glAttachShader(mTextureProgram, mTextureVertexShader);
+	glAttachShader(mTextureProgram, mTextureFragmentShader);
+	glLinkProgram(mTextureProgram);
+
+	GLint linkResult = GL_FALSE;
+	glGetProgramiv(mTextureProgram, GL_LINK_STATUS, &linkResult);
+	if (linkResult == GL_FALSE)
+	{
+		DestroyTextureProgram();
+		return false;
+	}
+
+	glUseProgram(mTextureProgram);
+	const GLint inputLocation = glGetUniformLocation(mTextureProgram, "uInputTexture");
+	if (inputLocation >= 0)
+		glUniform1i(inputLocation, static_cast<GLint>(kInputTextureUnit));
+	glUseProgram(0);
+
+	glGenVertexArrays(1, &mTextureVertexArray);
+	return mTextureVertexArray != 0;
+}
+
+void SimpleMotionRenderer::DestroyTextureProgram()
+{
+	if (mTextureProgram != 0)
+		glDeleteProgram(mTextureProgram);
+	if (mTextureVertexShader != 0)
+		glDeleteShader(mTextureVertexShader);
+	if (mTextureFragmentShader != 0)
+		glDeleteShader(mTextureFragmentShader);
+	if (mTextureVertexArray != 0)
+		glDeleteVertexArrays(1, &mTextureVertexArray);
+	mTextureProgram = 0;
+	mTextureVertexShader = 0;
+	mTextureFragmentShader = 0;
+	mTextureVertexArray = 0;
+}
+
+bool SimpleMotionRenderer::CompileShader(GLenum shaderType, const char* source, GLuint& shader)
+{
+	shader = glCreateShader(shaderType);
+	glShaderSource(shader, 1, &source, nullptr);
+	glCompileShader(shader);
+
+	GLint compileResult = GL_FALSE;
+	glGetShaderiv(shader, GL_COMPILE_STATUS, &compileResult);
+	if (compileResult != GL_FALSE)
+		return true;
+
+	glDeleteShader(shader);
+	shader = 0;
+	return false;
+}