implemented proper batch rendering of quads and textures

1 files changed, 195 insertions, 0 deletions

diff --git a/src/batch.cpp b/src/batch.cpp
new file mode 100644
index 0000000..d380e53
--- /dev/null
+++ b/src/batch.cpp
@@ -0,0 +1,195 @@
+#include "batch.hpp"
+
+#include <vector>
+#include <iostream>
+#include "glad/glad.h"
+
+#include "texture.hpp"
+
+
+Batch::Batch(unsigned int batch_limit)
+{
+	this->batch_limit = batch_limit;
+
+	glGenBuffers(1, &VBO); // generate the buffer
+	glGenBuffers(1, &EBO);
+	glGenVertexArrays(1, &VAO); // generate array
+
+	glBindVertexArray(VAO); // bind array to apply "settings" to it
+	glBindBuffer(GL_ARRAY_BUFFER, VBO); // bind(activate) the buffer to the ARRAY_BUFFER
+	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
+
+	// position attribute
+	GLsizei stride = 10 * sizeof(float);
+	glVertexAttribPointer(
+			0, // index
+			3, // size(number of elements)
+			GL_FLOAT,
+			GL_FALSE,
+			stride, // stride(distance to reach next one)
+			(void*)0); // pointer(offset from start)
+	glEnableVertexAttribArray(0);
+
+	// color attribute
+	glVertexAttribPointer(
+			1,
+			4,
+			GL_FLOAT,
+			GL_FALSE,
+			stride,
+			(void*)(3 * sizeof(float))); // configure how the vertex array looks
+	glEnableVertexAttribArray(1);
+
+	//texture coordinates
+	glVertexAttribPointer(
+			2,
+			2,
+			GL_FLOAT,
+			GL_FALSE,
+			stride,
+			(void*)(7 * sizeof(float))); // configure how the vertex array looks
+	glEnableVertexAttribArray(2);
+
+	//texture id
+	glVertexAttribPointer(
+			3,
+			1,
+			GL_FLOAT,
+			GL_FALSE,
+			stride,
+			(void*)(9 * sizeof(float))); // configure how the vertex array looks
+	glEnableVertexAttribArray(3);
+}
+
+int Batch::drawTexture(
+		Texture texture,
+		float x,
+		float y,
+		float width,
+		float height,
+		glm::vec4 color
+		)
+{
+	float h_height = height / 2.0;
+	float h_width = width / 2.0;
+	return this->primativeDrawQuad(
+			texture.id,
+			glm::vec3(x+h_height,y+h_width,0.0f), // top right
+			glm::vec3(x+h_height, y-h_width, 0.0f), // bottom right
+			glm::vec3(x-h_height, y-h_width, 0.0f), // bottom left
+			glm::vec3(x-h_height, y+h_height, 0.0f), // top left 
+			color
+			);
+}
+
+
+int Batch::drawRectangle(
+		float x,
+		float y,
+		float width,
+		float height,
+		glm::vec4 color
+		)
+{
+	float h_height = height / 2.0;
+	float h_width = width / 2.0;
+	return this->primativeDrawQuad(
+			0,
+			glm::vec3(x+h_height,y+h_width,0.0f), // top right
+			glm::vec3(x+h_height, y-h_width, 0.0f), // bottom right
+			glm::vec3(x-h_height, y-h_width, 0.0f), // bottom left
+			glm::vec3(x-h_height, y+h_height, 0.0f), // top left 
+			color
+			);
+}
+
+int Batch::primativeDrawQuad(
+		unsigned int texture_id,
+		glm::vec3 a,
+		glm::vec3 b,
+		glm::vec3 c,
+		glm::vec3 d,
+		glm::vec4 color
+		)
+{
+	// if no assigned texture, attempt to assign it
+	if(texture_id == 0)
+		last_texture = texture_id;
+	// if surpassing batch limit
+	// or if texture is different
+	if((size >= batch_limit) || ((last_texture != texture_id) && (texture_id != 0)))
+		this->flush_batch(); last_texture = texture_id;
+
+
+	float verts[] = {
+		// top right	
+		a.x,  a.y, a.z, // position
+		color.r, color.g, color.b, color.a, // colors
+		1.0f, 1.0f, // tex coords
+		(float)texture_id, // tex id(0 means none)
+
+		// bottom right
+		b.x, b.y, b.z,
+		color.r, color.g, color.b, color.a,
+		1.0f, 0.0f,
+		(float)texture_id,
+
+		// bottom left
+		c.x, c.y, c.z,
+		color.r, color.g, color.b, color.a,
+		0.0f, 0.0f,
+		(float)texture_id,  
+
+		// top left 
+		d.x,  d.y, d.z,
+		color.r, color.g, color.b, color.a,
+		0.0f, 1.0f,
+		(float)texture_id  
+	};
+	unsigned int inds[] = {
+		(size * 4) + 0, (size * 4) + 1, (size * 4) + 3,  // first triangle
+		(size * 4) + 1, (size * 4) + 2, (size * 4) + 3,  // second triangle
+	};
+	vertices.reserve(sizeof(verts));
+	indices.reserve(sizeof(inds));
+	vertices.insert(vertices.end(), std::cbegin(verts), std::cend(verts));
+	indices.insert(indices.end(), std::cbegin(inds), std::cend(inds));
+	size += 1;
+
+	return 0;
+}
+
+void Batch::flush_batch()
+{
+	glBindVertexArray(VAO);
+
+	// we already binded this in the VAO during initialization
+	// so no need to do it again
+	//glBindBuffer(GL_ARRAY_BUFFER, VBO);
+	glBufferData( // uploading vertices
+			GL_ARRAY_BUFFER,
+			vertices.size() * sizeof(float),
+			vertices.data(),
+			GL_STATIC_DRAW
+			);
+
+	// we already binded this in the VAO during initialization
+	// so no need to do it again
+	//glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
+	glBufferData( // uploading indices
+			GL_ELEMENT_ARRAY_BUFFER,
+			indices.size() * sizeof(unsigned int),
+			indices.data(),
+			GL_STATIC_DRAW
+			);
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D, last_texture);
+	glDrawElements(GL_TRIANGLES, 6 * size, GL_UNSIGNED_INT, 0);
+
+	glBindVertexArray(0); // unbind the VAO
+
+	last_texture = -1;
+	size = 0;
+	vertices.clear();
+	indices.clear();
+}