&globe &globe

.gitmodules

@@ -1,3 +1,6 @@
 [submodule "digraphene-headers"]
 	path = digraphene-headers
 	url = https://gitlab.com/TestingPlant/digraphene-headers.git
+[submodule "stb"]
+	path = stb
+	url = https://github.com/nothings/stb.git

native/main.cpp

@@ -14,13 +14,14 @@
     You should have received a copy of the GNU General Public License
     along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
+#define STB_IMAGE_IMPLEMENTATION
+#include <stb_image.h>
 #include <mesh.h>
 #include <GLFW/glfw3.h>
 #include <shader.h>
 #include <cstring>
 #include <cassert>
 #include <iostream>
-#include <type_traits>
 
 typedef struct {
 	linalg::aliases::float2 position;
@@ -122,6 +123,16 @@ int main() {
 	GLFWwindow* window = glfwCreateWindow(resultLength, resultLength, "You aren't supposed to see this", NULL, NULL);
 	glfwMakeContextCurrent(window);
 
+	int contextFlags;
+	glGetIntegerv(GL_CONTEXT_FLAGS, &contextFlags);
+	if (contextFlags & GL_CONTEXT_FLAG_DEBUG_BIT) {
+		glEnable(GL_DEBUG_OUTPUT);
+		glDebugMessageCallback(onDebugOutput, NULL);
+		glDebugMessageControl(GL_DONT_CARE, GL_DONT_CARE, GL_DONT_CARE, 0, NULL, GL_TRUE);
+	} else {
+		std::cerr << "Warning: Debug context could not be created.\n";
+	}
+
 	// Load a square
 	/*
 		0--1
@@ -170,13 +181,15 @@ int main() {
 	shader.use();
 
 	// Set up a framebuffer
-	/*unsigned int frameBuffer;
+	unsigned int frameBuffer;
 	glGenFramebuffers(1, &frameBuffer);
 	glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer);
 	unsigned int colorBuffer;
 	glGenTextures(1, &colorBuffer);
 	glBindTexture(GL_TEXTURE_2D, colorBuffer);
-	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, resultLength, resultLength, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
+	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, resultLength, resultLength, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, colorBuffer, 0);
 	unsigned int renderBuffer;
 	glGenRenderbuffers(1, &renderBuffer);
@@ -185,13 +198,48 @@ int main() {
 	glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, renderBuffer);
 
 	assert(glCheckFramebufferStatus(GL_FRAMEBUFFER) == GL_FRAMEBUFFER_COMPLETE && "Generated framebuffer is incomplete");
-*/
 
-	glClearColor(0.5, 0, 0, 1);
+	unsigned int texture, normal;
-	glEnable(GL_BLEND);
+	// Load the image
-	glBlendFunc(GL_SRC_ALPHA, GL_SRC_ALPHA);
+	{
-	while (!glfwWindowShouldClose(window)) {
+		int width, height;
+		unsigned char* data = stbi_load("../test.png", &width, &height, nullptr, 0);
+		glGenTextures(1, &texture);
+		glBindTexture(GL_TEXTURE_2D, texture);
+		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
+		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
+		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
+		glGenerateMipmap(GL_TEXTURE_2D);
+		stbi_image_free(data);
+
+		glUniform1i(glGetUniformLocation(shader.id, "aTexture"), 0);
+	}
+
+	glClearColor(0.25, 0.25, 0.25, 1);
 	glClear(GL_COLOR_BUFFER_BIT);
+	glEnable(GL_BLEND);
+	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+	const float increment = -1.0f/30.0f;
+	float offset = 0;
+	while (!glfwWindowShouldClose(window)) {
+		glUniform1f(glGetUniformLocation(shader.id, "aHorizontalOffset"), offset);
+		offset += increment;
+		if (offset <= -1)
+			offset = 0;
+
+		glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer);
+		glUniform1f(glGetUniformLocation(shader.id, "aTexCoordYScale"), -1);
+		glActiveTexture(GL_TEXTURE0);
+		glBindTexture(GL_TEXTURE_2D, texture);
+		square.draw();
+
+		glBindFramebuffer(GL_FRAMEBUFFER, 0);
+		glUniform1f(glGetUniformLocation(shader.id, "aTexCoordYScale"), 1);
+		glClear(GL_COLOR_BUFFER_BIT);
+		glActiveTexture(GL_TEXTURE0);
+		glBindTexture(GL_TEXTURE_2D, colorBuffer);
 		square.draw();
 		glfwSwapBuffers(window);
 		glfwPollEvents();

shaders/fragment.glsl

@@ -5,28 +5,33 @@
     it under the terms of the GNU General Public License as published by
     the Free Software Foundation, either version 3 of the License, or
     (at your option) any later version.
+
     This program is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU General Public License for more details.
+
     You should have received a copy of the GNU General Public License
     along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
 #version 330 core
 
-in vec2 vTexCoord;
+in vec2 vFragCoord;
 
-uniform sampler2D aTexture0;
+uniform float aHorizontalOffset;
+uniform sampler2D aTexture;
 
 void main() {
-	/*
+	float distanceFromCenterSquared = dot(vFragCoord, vFragCoord);
-		dot(vTexCoord, vTexCoord)
-		essentially does pow(length(gl_FragCoord.xy),2), but
-		(probably) more optimized
 
-		We're doing this since we don't want fragments outside a circle
+	// alpha = 0 if fragment is outside circle
-	*/
+	// alpha = 1 if fragment is inside circle
-	float alpha = dot(vTexCoord, vTexCoord) > 1 ? 1 : 0;
+	float alpha = distanceFromCenterSquared > 1 ? 0 : 1;
 
-	gl_FragColor = vec4(0, 0, 0, alpha);
+	// An equation which seems to work
+	float specular = distanceFromCenterSquared * (-0.5f*vFragCoord.x + vFragCoord.y) + 1;
+
+	vec2 texCoord = vFragCoord * vec2(0.5,0.5) + vec2(0.5+aHorizontalOffset,0.5);
+
+	gl_FragColor = vec4(texture(aTexture, texCoord).xyz*specular, alpha);
 }

shaders/vertex.glsl

@@ -18,9 +18,12 @@
 
 layout (location = 0) in vec2 aPosition;
 
-out vec2 vTexCoord;
+out vec2 vFragCoord;
+
+// Set to 1 or -1 to flip Y
+uniform float aTexCoordYScale;
 
 void main() {
 	gl_Position = vec4(aPosition, 0, 1);
-	vTexCoord = aPosition;
+	vFragCoord = aPosition * vec2(1, aTexCoordYScale);
 }

stb

@@ -0,0 +1 @@
+Subproject commit b42009b3b9d4ca35bc703f5310eedc74f584be58