opengl_learn

commit 6d0b1f454360a1c91091f453598e702af56de31d
parent 6455b97b23ccf06f3dd8d4f42fd5e6cf83bda2e9
Author: David DiPaola <DavidDiPaola@users.noreply.github.com>
Date:   Wed, 27 Jun 2018 07:56:15 -0400

03: renamed shader variables to be more clear

Diffstat:
M
03-texture.c
 | 
60
+++++++++++++++++++++++++++++++-----------------------------

1 file changed, 31 insertions(+), 29 deletions(-)
diff --git a/03-texture.c b/03-texture.c
@@ -25,37 +25,39 @@ int
 main() {
 	GLFWwindow * window = ogl_init(400, 240, "03 - texture");
 
+	/* vu: vertex uniform,  va: vertex attribute,  fu: fragment uniform,  fv: fragment varying */
 	const char * program_vertex_source =
 		"#version 100" "\n"
 		"precision highp float;" "\n"
-		"uniform   mat4 uniform_MVP;" "\n"         /* uniforms are inputs to vertex shaders that don't change per-vertex */
-		"attribute vec3 attribute_position;" "\n"  /* attributes are inputs to vertex shaders */
-		"attribute vec3 attribute_color;" "\n"
-		"attribute vec2 attribute_UV;" "\n"
-		"varying   vec4 varying_color;" "\n"       /* varyings are outputs of vertex shaders and inputs to fragment shaders */
-		"varying   vec2 varying_UV;" "\n"
+		"uniform   mat4 vu_vertex_MVP;" "\n"       /* uniforms are inputs to vertex and fragment shaders that don't change per-vertex */
+		"attribute vec3 va_vertex_position;" "\n"  /* attributes are inputs to vertex shaders */
+		"attribute vec3 va_vertex_color;" "\n"
+		"attribute vec2 va_texture_UV;" "\n"
+		"varying   vec4 fv_vertex_color;" "\n"     /* varyings are outputs of vertex shaders and inputs to fragment shaders */
+		"varying   vec2 fv_texture_UV;" "\n"
 		"void main(){" "\n"
-		"	gl_Position   = uniform_MVP * vec4(attribute_position,1);" "\n"
-		"	varying_color = vec4(attribute_color,1);" "\n"
-		"	varying_UV    = attribute_UV;" "\n"
+		"	gl_Position = vu_vertex_MVP * vec4(va_vertex_position,1);" "\n"
+		"\n"
+		"	fv_vertex_color = vec4(va_vertex_color,1);" "\n"
+		"	fv_texture_UV   = va_texture_UV;" "\n"
 		"}" "\n"
 	;
 	const char * program_fragment_source =
 		"#version 100" "\n"
 		"precision lowp float;" "\n"
-		"uniform sampler2D uniform_texturesampler;" "\n"
-		"varying vec4      varying_color;" "\n"
-		"varying vec2      varying_UV;" "\n"
+		"uniform sampler2D fu_texture_sampler;" "\n"
+		"varying vec2      fv_texture_UV;" "\n"
+		"varying vec4      fv_vertex_color;" "\n"
 		"void main() {" "\n"
-		"	vec4 texturesampler_color = texture2D(uniform_texturesampler, varying_UV);" "\n"
-		"	gl_FragColor = mix(texturesampler_color, varying_color, 1.0-texturesampler_color.a);" "\n"
+		"	vec4 texel = texture2D(fu_texture_sampler, fv_texture_UV);" "\n"
+		"	gl_FragColor = mix(texel, fv_vertex_color, 1.0-texel.a);" "\n"
 		"}" "\n"
 	;
 	GLuint program_ID = ogl_program_build(program_vertex_source, program_fragment_source);
-	GLint program_uniform_texturesampler_ID = glGetUniformLocation(program_ID, "uniform_texturesampler");
-	GLint program_attribute_position_ID     = glGetAttribLocation( program_ID, "attribute_position");
-	GLint program_attribute_color_ID        = glGetAttribLocation( program_ID, "attribute_color");
-	GLint program_attribute_UV_ID           = glGetAttribLocation( program_ID, "attribute_UV");
+	GLint program_va_vertex_position_ID = glGetAttribLocation( program_ID, "va_vertex_position");
+	GLint program_va_vertex_color_ID    = glGetAttribLocation( program_ID, "va_vertex_color");
+	GLint program_va_texture_UV_ID      = glGetAttribLocation( program_ID, "va_texture_UV");
+	GLint program_fu_texture_sampler_ID = glGetUniformLocation(program_ID, "fu_texture_sampler");
 
 	struct ogl_mat4f MVP_projection;
 	ogl_perspective(45.0f, 0.1f, 100.0f, &MVP_projection);
@@ -147,29 +149,29 @@ main() {
 		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
 		glUseProgram(program_ID);
-		ogl_program_uniform_set_mat4f(program_ID, "uniform_MVP", MVP);
+		ogl_program_uniform_set_mat4f(program_ID, "vu_vertex_MVP", MVP);
 		glActiveTexture(GL_TEXTURE0);
 		glBindTexture(GL_TEXTURE_2D, cube_texture_ID);
-		glUniform1i(program_uniform_texturesampler_ID, 0);
+		glUniform1i(program_fu_texture_sampler_ID, 0);
 
-		glEnableVertexAttribArray(program_attribute_position_ID);
+		glEnableVertexAttribArray(program_va_vertex_position_ID);
 		glBindBuffer(GL_ARRAY_BUFFER, cube_vertexbuffer_ID);
-		glVertexAttribPointer(program_attribute_position_ID, 3, GL_FLOAT, GL_FALSE, 0, (GLvoid *)0);
+		glVertexAttribPointer(program_va_vertex_position_ID, 3, GL_FLOAT, GL_FALSE, 0, (GLvoid *)0);
 
-		glEnableVertexAttribArray(program_attribute_UV_ID);
+		glEnableVertexAttribArray(program_va_texture_UV_ID);
 		glBindBuffer(GL_ARRAY_BUFFER, cube_texture_UVbuffer_ID);
-		glVertexAttribPointer(program_attribute_UV_ID, 2, GL_FLOAT, GL_FALSE, 0, (GLvoid *)0);
+		glVertexAttribPointer(program_va_texture_UV_ID, 2, GL_FLOAT, GL_FALSE, 0, (GLvoid *)0);
 
-		glEnableVertexAttribArray(program_attribute_color_ID);
+		glEnableVertexAttribArray(program_va_vertex_color_ID);
 		glBindBuffer(GL_ARRAY_BUFFER, cube_colorbuffer_ID);
-		glVertexAttribPointer(program_attribute_color_ID, 3, GL_FLOAT, GL_FALSE, 0, (GLvoid *)0);
+		glVertexAttribPointer(program_va_vertex_color_ID, 3, GL_FLOAT, GL_FALSE, 0, (GLvoid *)0);
 
 		glDrawArrays(GL_TRIANGLES, 0, cube_vertexbuffer_data_vertexes);
 
 		glBindBuffer(GL_ARRAY_BUFFER, 0);
-		glDisableVertexAttribArray(program_attribute_position_ID);
-		glDisableVertexAttribArray(program_attribute_UV_ID);
-		//glDisableVertexAttribArray(program_attribute_color_ID);
+		glDisableVertexAttribArray(program_va_vertex_position_ID);
+		glDisableVertexAttribArray(program_va_texture_UV_ID);
+		//glDisableVertexAttribArray(program_va_vertex_color_ID);
 
 		glfwSwapBuffers(window);
 		glfwPollEvents();